{
  "title": "Infinite solutions (Linear Equations in Two Variables) - Grade 9 CBSE",
  "total_questions": 100,
  "questions": [
    {"id": 1, "difficulty": "easy", "question": "When do two linear equations have infinite solutions?", "options": {"A": "Same slope, different intercept", "B": "Different slopes", "C": "Same slope and same intercept", "D": "Parallel lines"}, "correct_answer": "A"},
    {"id": 2, "difficulty": "easy", "question": "System: 2x+3y=6 and 4x+6y=12 has:", "options": {"A": "Unique solution", "B": "No solution", "C": "Infinite solutions", "D": "Two solutions"}, "correct_answer": "C"},
    {"id": 3, "difficulty": "easy", "question": "If a1/a2 = b1/b2 = c1/c2, then lines are:", "options": {"A": "Parallel", "B": "Intersecting", "C": "Coincident", "D": "Perpendicular"}, "correct_answer": "C"},
    {"id": 4, "difficulty": "easy", "question": "Coincident lines have how many solutions?", "options": {"A": "0", "B": "1", "C": "2", "D": "Infinite"}, "correct_answer": "D"},
    {"id": 5, "difficulty": "easy", "question": "Equations y=2x+3 and 2y=4x+6 represent:", "options": {"A": "Parallel lines", "B": "Intersecting lines", "C": "Same line", "D": "Perpendicular lines"}, "correct_answer": "C"},
    {"id": 6, "difficulty": "easy", "question": "For infinite solutions, lines must be:", "options": {"A": "Parallel", "B": "Coincident", "C": "Intersecting", "D": "Skew"}, "correct_answer": "B"},
    {"id": 7, "difficulty": "easy", "question": "System x+y=3, 2x+2y=6 has:", "options": {"A": "No solution", "B": "Unique", "C": "Infinite solutions", "D": "Three solutions"}, "correct_answer": "C"},
    {"id": 8, "difficulty": "easy", "question": "If equations are multiples of each other, they have:", "options": {"A": "No solution", "B": "One solution", "C": "Infinite solutions", "D": "Two solutions"}, "correct_answer": "C"},
    {"id": 9, "difficulty": "easy", "question": "Which condition gives infinite solutions?", "options": {"A": "a1/a2 ≠ b1/b2", "B": "a1/a2 = b1/b2 ≠ c1/c2", "C": "a1/a2 = b1/b2 = c1/c2", "D": "a1/a2 = b1/b2 = 1"}, "correct_answer": "C"},
    {"id": 10, "difficulty": "easy", "question": "Lines representing infinite solutions are:", "options": {"A": "Parallel", "B": "Coincident", "C": "Intersecting at one point", "D": "Perpendicular"}, "correct_answer": "B"},
    {"id": 11, "difficulty": "easy", "question": "Equation 3x+2y=5 and 6x+4y=10 are:", "options": {"A": "Different lines", "B": "Same line", "C": "Parallel", "D": "Intersecting"}, "correct_answer": "B"},
    {"id": 12, "difficulty": "easy", "question": "If second equation is double of first, solutions are:", "options": {"A": "Unique", "B": "Infinite", "C": "None", "D": "Two"}, "correct_answer": "B"},
    {"id": 13, "difficulty": "easy", "question": "System with infinite solutions means:", "options": {"A": "Lines meet at origin", "B": "Lines coincide", "C": "Lines are parallel", "D": "Lines are perpendicular"}, "correct_answer": "B"},
    {"id": 14, "difficulty": "easy", "question": "Check: x+2y=4 and 2x+4y=8 have:", "options": {"A": "Unique solution", "B": "No solution", "C": "Infinite solutions", "D": "Exactly two solutions"}, "correct_answer": "C"},
    {"id": 15, "difficulty": "easy", "question": "Graphically, infinite solutions appear as:", "options": {"A": "Two parallel lines", "B": "Two intersecting lines", "C": "Single line", "D": "Two perpendicular lines"}, "correct_answer": "C"},
    {"id": 16, "difficulty": "easy", "question": "If kx+2y=5 and 3x+6y=15 have infinite solutions, find k.", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "A"},
    {"id": 17, "difficulty": "easy", "question": "Equations y=3x+2 and 3y=9x+6 have:", "options": {"A": "No solution", "B": "One solution", "C": "Infinite solutions", "D": "Two solutions"}, "correct_answer": "C"},
    {"id": 18, "difficulty": "easy", "question": "For infinite solutions, ratio of coefficients must be:", "options": {"A": "Different", "B": "Equal", "C": "Reciprocal", "D": "Negative"}, "correct_answer": "B"},
    {"id": 19, "difficulty": "easy", "question": "System 4x-2y=8 and 2x-y=4 has:", "options": {"A": "Unique solution", "B": "No solution", "C": "Infinite solutions", "D": "Three solutions"}, "correct_answer": "C"},
    {"id": 20, "difficulty": "easy", "question": "If lines coincide, they have:", "options": {"A": "Zero solutions", "B": "One solution", "C": "Infinite solutions", "D": "Two solutions"}, "correct_answer": "C"},
    {"id": 21, "difficulty": "medium", "question": "Find k if 2x+3y=7 and kx+6y=14 have infinite solutions.", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "C"},
    {"id": 22, "difficulty": "medium", "question": "For what value of p: px+2y=5, 3x+6y=15 have infinite solutions?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "A"},
    {"id": 23, "difficulty": "medium", "question": "System: (k-1)x+2y=3, 3x+6y=9 has infinite solutions. Find k.", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "A"},
    {"id": 24, "difficulty": "medium", "question": "If 4x+py=8 and 2x+3y=6 have infinite solutions, find p.", "options": {"A": "3", "B": "4", "C": "6", "D": "8"}, "correct_answer": "C"},
    {"id": 25, "difficulty": "medium", "question": "For infinite solutions of ax+2y=5, 3x+6y=15, find a.", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "A"},
    {"id": 26, "difficulty": "medium", "question": "Find k if lines 2x+3y=7 and 4x+ky=14 coincide.", "options": {"A": "3", "B": "4", "C": "5", "D": "6"}, "correct_answer": "D"},
    {"id": 27, "difficulty": "medium", "question": "System: 3x+4y=12, 6x+8y=k has infinite solutions. Find k.", "options": {"A": "12", "B": "18", "C": "24", "D": "36"}, "correct_answer": "C"},
    {"id": 28, "difficulty": "medium", "question": "If 5x+2y=10 and 10x+4y=k have infinite solutions, k=?", "options": {"A": "10", "B": "15", "C": "20", "D": "25"}, "correct_answer": "C"},
    {"id": 29, "difficulty": "medium", "question": "For what p: 2x+py=8, x+3y=4 have infinite solutions?", "options": {"A": "3", "B": "4", "C": "5", "D": "6"}, "correct_answer": "D"},
    {"id": 30, "difficulty": "medium", "question": "System: (a-1)x+3y=2, 6x+(b+1)y=6 has infinite solutions. Find relation between a,b.", "options": {"A": "a=3,b=2", "B": "a=2,b=8", "C": "a=7,b=2", "D": "a=4,b=5"}, "correct_answer": "C"},
    {"id": 31, "difficulty": "medium", "question": "If lines 3x+2y=6 and 6x+4y=k coincide, k=?", "options": {"A": "6", "B": "12", "C": "18", "D": "24"}, "correct_answer": "B"},
    {"id": 32, "difficulty": "medium", "question": "Find k for infinite solutions: kx+3y=9, 2x+6y=18.", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "A"},
    {"id": 33, "difficulty": "medium", "question": "System: 2x+5y=10, 4x+10y=20 has:", "options": {"A": "Unique", "B": "No solution", "C": "Infinite", "D": "Two solutions"}, "correct_answer": "C"},
    {"id": 34, "difficulty": "medium", "question": "If 7x+3y=14 and 14x+6y=28, they are:", "options": {"A": "Parallel", "B": "Intersecting", "C": "Coincident", "D": "Perpendicular"}, "correct_answer": "C"},
    {"id": 35, "difficulty": "medium", "question": "For infinite solutions of px+2y=6, 3x+y=3, find p.", "options": {"A": "3", "B": "6", "C": "9", "D": "12"}, "correct_answer": "B"},
    {"id": 36, "difficulty": "medium", "question": "If lines 4x+ky=8 and 2x+3y=6 are coincident, k=?", "options": {"A": "3", "B": "4", "C": "6", "D": "8"}, "correct_answer": "C"},
    {"id": 37, "difficulty": "medium", "question": "System: (k+1)x+2y=5, 3x+6y=15 has infinite solutions. Find k.", "options": {"A": "0", "B": "1", "C": "2", "D": "3"}, "correct_answer": "A"},
    {"id": 38, "difficulty": "medium", "question": "For what a,b: ax+2y=5, 3x+by=15 have infinite solutions?", "options": {"A": "a=1,b=6", "B": "a=2,b=4", "C": "a=3,b=2", "D": "a=4,b=8"}, "correct_answer": "A"},
    {"id": 39, "difficulty": "medium", "question": "If 5x+ky=10 and 10x+20y=40 have infinite solutions, k=?", "options": {"A": "5", "B": "10", "C": "15", "D": "20"}, "correct_answer": "B"},
    {"id": 40, "difficulty": "medium", "question": "Find p for coincident lines: 2x+3y=7, px+6y=14.", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "C"},
    {"id": 41, "difficulty": "medium", "question": "System: 3x+4y=12, 9x+12y=36 represents:", "options": {"A": "Parallel lines", "B": "Intersecting lines", "C": "Coincident lines", "D": "Perpendicular lines"}, "correct_answer": "C"},
    {"id": 42, "difficulty": "medium", "question": "If lines are coincident, they satisfy condition:", "options": {"A": "a1/a2 ≠ b1/b2", "B": "a1/a2 = b1/b2 ≠ c1/c2", "C": "a1/a2 = b1/b2 = c1/c2", "D": "a1a2 + b1b2 = 0"}, "correct_answer": "C"},
    {"id": 43, "difficulty": "medium", "question": "For infinite solutions: 2x+py=8, 4x+8y=16, find p.", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "C"},
    {"id": 44, "difficulty": "medium", "question": "If kx+6y=12 and 3x+2y=6 have infinite solutions, k=?", "options": {"A": "3", "B": "6", "C": "9", "D": "12"}, "correct_answer": "C"},
    {"id": 45, "difficulty": "medium", "question": "System: 5x+2y=10, 10x+4y=20 has how many solutions?", "options": {"A": "0", "B": "1", "C": "Infinite", "D": "2"}, "correct_answer": "C"},
    {"id": 46, "difficulty": "medium", "question": "Find a for infinite solutions: ax+4y=8, 3x+6y=12.", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "B"},
    {"id": 47, "difficulty": "medium", "question": "If lines 2x+5y=10 and 4x+10y=k coincide, k=?", "options": {"A": "10", "B": "15", "C": "20", "D": "25"}, "correct_answer": "C"},
    {"id": 48, "difficulty": "medium", "question": "For what k: kx+3y=6, 2x+6y=12 have infinite solutions?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "A"},
    {"id": 49, "difficulty": "medium", "question": "System: 3x-y=6, 6x-2y=12 has:", "options": {"A": "Unique solution", "B": "No solution", "C": "Infinite solutions", "D": "Two solutions"}, "correct_answer": "C"},
    {"id": 50, "difficulty": "medium", "question": "If 4x+ky=8 and 8x+16y=32 have infinite solutions, k=?", "options": {"A": "4", "B": "6", "C": "8", "D": "10"}, "correct_answer": "C"},
    {"id": 51, "difficulty": "medium", "question": "Find p for coincident lines: px+2y=6, 3x+6y=18.", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "A"},
    {"id": 52, "difficulty": "medium", "question": "If lines are multiples: 3x+4y=7 and 6x+8y=14, they are:", "options": {"A": "Parallel", "B": "Coincident", "C": "Intersecting", "D": "Perpendicular"}, "correct_answer": "B"},
    {"id": 53, "difficulty": "medium", "question": "For infinite solutions: 2x+3y=5, 4x+6y=k, find k.", "options": {"A": "5", "B": "10", "C": "15", "D": "20"}, "correct_answer": "B"},
    {"id": 54, "difficulty": "medium", "question": "System: 7x+2y=14, 14x+4y=28 has how many solutions?", "options": {"A": "0", "B": "1", "C": "Infinite", "D": "2"}, "correct_answer": "C"},
    {"id": 55, "difficulty": "medium", "question": "If a1/a2 = b1/b2 = c1/c2 = 2, lines are:", "options": {"A": "Parallel", "B": "Coincident", "C": "Intersecting", "D": "Same slope different intercept"}, "correct_answer": "B"},
    {"id": 56, "difficulty": "medium", "question": "Find k for infinite solutions: 3x+ky=9, 6x+12y=18.", "options": {"A": "4", "B": "5", "C": "6", "D": "7"}, "correct_answer": "C"},
    {"id": 57, "difficulty": "medium", "question": "If lines 5x+2y=10 and 10x+4y=20 are same, they have:", "options": {"A": "One solution", "B": "No solution", "C": "Infinite solutions", "D": "Two solutions"}, "correct_answer": "C"},
    {"id": 58, "difficulty": "medium", "question": "For what p: px+4y=12, 3x+12y=36 have infinite solutions?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "A"},
    {"id": 59, "difficulty": "medium", "question": "System: 2x+5y=10, 4x+10y=20 graphically gives:", "options": {"A": "Two parallel lines", "B": "Two intersecting lines", "C": "Single line", "D": "Two perpendicular lines"}, "correct_answer": "C"},
    {"id": 60, "difficulty": "medium", "question": "If kx+8y=16 and 2x+4y=8 have infinite solutions, k=?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "C"},
    {"id": 61, "difficulty": "medium", "question": "Find a for coincident lines: ax+6y=12, 4x+8y=16.", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "B"},
    {"id": 62, "difficulty": "medium", "question": "If 3x+4y=12 and 6x+8y=24, they represent:", "options": {"A": "Different lines", "B": "Same line", "C": "Parallel lines", "D": "Intersecting lines"}, "correct_answer": "B"},
    {"id": 63, "difficulty": "medium", "question": "For infinite solutions: 5x+2y=10, 10x+ky=20, find k.", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "C"},
    {"id": 64, "difficulty": "medium", "question": "System: x+2y=4, 2x+4y=8 has solutions:", "options": {"A": "(0,2) only", "B": "(2,0) only", "C": "Infinite", "D": "No solution"}, "correct_answer": "C"},
    {"id": 65, "difficulty": "medium", "question": "If lines are coincident, number of solutions is:", "options": {"A": "0", "B": "1", "C": "2", "D": "Infinite"}, "correct_answer": "D"},
    {"id": 66, "difficulty": "medium", "question": "Find k for infinite solutions: 2x+3y=7, kx+6y=14.", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "C"},
    {"id": 67, "difficulty": "medium", "question": "If a1=2, b1=3, c1=6 and a2=4, b2=6, c2=12, lines are:", "options": {"A": "Parallel", "B": "Coincident", "C": "Intersecting", "D": "Perpendicular"}, "correct_answer": "B"},
    {"id": 68, "difficulty": "medium", "question": "For what p: px+5y=10, 3x+15y=30 have infinite solutions?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "A"},
    {"id": 69, "difficulty": "medium", "question": "System: 4x+3y=12, 8x+6y=24 has:", "options": {"A": "Unique solution", "B": "No solution", "C": "Infinite solutions", "D": "Two solutions"}, "correct_answer": "C"},
    {"id": 70, "difficulty": "medium", "question": "If lines 2x+7y=14 and 4x+14y=28 coincide, they have:", "options": {"A": "One solution", "B": "No solution", "C": "Infinite solutions", "D": "Two solutions"}, "correct_answer": "C"},
    {"id": 71, "difficulty": "medium", "question": "Find k for infinite solutions: kx+4y=8, 6x+8y=16.", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "B"},
    {"id": 72, "difficulty": "medium", "question": "If 3x+2y=6 and 6x+4y=12 are same line, solutions are:", "options": {"A": "Finite", "B": "Infinite", "C": "Zero", "D": "Exactly two"}, "correct_answer": "B"},
    {"id": 73, "difficulty": "medium", "question": "For infinite solutions: 7x+2y=14, 14x+ky=28, find k.", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "C"},
    {"id": 74, "difficulty": "medium", "question": "System: 5x+3y=15, 10x+6y=30 represents:", "options": {"A": "Parallel lines", "B": "Intersecting lines", "C": "Coincident lines", "D": "Perpendicular lines"}, "correct_answer": "C"},
    {"id": 75, "difficulty": "medium", "question": "If a1/a2 = b1/b2 = c1/c2 = 3, lines are:", "options": {"A": "Different", "B": "Parallel", "C": "Coincident", "D": "Intersecting at (3,3)"}, "correct_answer": "C"},
    {"id": 76, "difficulty": "medium", "question": "Find p for infinite solutions: 2x+py=10, 4x+10y=20.", "options": {"A": "3", "B": "4", "C": "5", "D": "6"}, "correct_answer": "C"},
    {"id": 77, "difficulty": "medium", "question": "If lines 4x+5y=20 and 8x+10y=40 are multiples, they have:", "options": {"A": "One solution", "B": "No solution", "C": "Infinite solutions", "D": "Two solutions"}, "correct_answer": "C"},
    {"id": 78, "difficulty": "medium", "question": "For what k: kx+6y=18, 2x+4y=12 have infinite solutions?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "B"},
    {"id": 79, "difficulty": "medium", "question": "System: 6x+4y=12, 12x+8y=24 has how many solutions?", "options": {"A": "0", "B": "1", "C": "Infinite", "D": "2"}, "correct_answer": "C"},
    {"id": 80, "difficulty": "medium", "question": "If lines are same, condition is:", "options": {"A": "a1/a2 ≠ b1/b2", "B": "a1/a2 = b1/b2 ≠ c1/c2", "C": "a1/a2 = b1/b2 = c1/c2", "D": "a1a2 + b1b2 = 0"}, "correct_answer": "C"},
    {"id": 81, "difficulty": "hard", "question": "Find k and m for infinite solutions: (k-2)x+3y=7, 2x+(m+1)y=14.", "options": {"A": "k=4,m=5", "B": "k=6,m=2", "C": "k=3,m=4", "D": "k=5,m=8"}, "correct_answer": "A"},
    {"id": 82, "difficulty": "hard", "question": "For what a,b: ax+2y=8, 3x+by=12 have infinite solutions and a+b=10?", "options": {"A": "a=4,b=6", "B": "a=6,b=4", "C": "a=2,b=8", "D": "a=8,b=2"}, "correct_answer": "B"},
    {"id": 83, "difficulty": "hard", "question": "System: (p+1)x+2y=5, 3x+(q-1)y=10 has infinite solutions. Find p/q if p+q=8.", "options": {"A": "1/3", "B": "1/2", "C": "2/3", "D": "3/4"}, "correct_answer": "A"},
    {"id": 84, "difficulty": "hard", "question": "Lines (k-3)x+4y=12 and 2x+(k+1)y=24 are coincident. Find k.", "options": {"A": "5", "B": "6", "C": "7", "D": "8"}, "correct_answer": "C"},
    {"id": 85, "difficulty": "hard", "question": "For infinite solutions of ax+by=8 and 3x+4y=12, if a:b=3:4, find a,b.", "options": {"A": "a=3,b=4", "B": "a=6,b=8", "C": "a=9,b=12", "D": "a=12,b=16"}, "correct_answer": "B"},
    {"id": 86, "difficulty": "hard", "question": "Find p and q if px+qy=12 and 3x+4y=6 have infinite solutions and p+q=14.", "options": {"A": "p=6,q=8", "B": "p=8,q=6", "C": "p=10,q=4", "D": "p=12,q=2"}, "correct_answer": "A"},
    {"id": 87, "difficulty": "hard", "question": "System: (a-1)x+(b+2)y=5, 2x+4y=10 has infinite solutions. If a-b=3, find a,b.", "options": {"A": "a=4,b=1", "B": "a=5,b=2", "C": "a=6,b=3", "D": "a=7,b=4"}, "correct_answer": "B"},
    {"id": 88, "difficulty": "hard", "question": "Lines kx+3y=9 and 4x+my=18 coincide. If k+m=10, find k,m.", "options": {"A": "k=2,m=8", "B": "k=3,m=7", "C": "k=4,m=6", "D": "k=5,m=5"}, "correct_answer": "A"},
    {"id": 89, "difficulty": "hard", "question": "For infinite solutions: (p+2)x+5y=15, 3x+(q-1)y=9. If p=2q, find p,q.", "options": {"A": "p=4,q=2", "B": "p=6,q=3", "C": "p=8,q=4", "D": "p=10,q=5"}, "correct_answer": "B"},
    {"id": 90, "difficulty": "hard", "question": "Find a,b such that ax+by=20 and 4x+5y=10 have infinite solutions and a-b=6.", "options": {"A": "a=12,b=6", "B": "a=14,b=8", "C": "a=16,b=10", "D": "a=18,b=12"}, "correct_answer": "C"},
    {"id": 91, "difficulty": "hard", "question": "System: (k-2)x+3y=6, 4x+(m+1)y=12 has infinite solutions. If k=m, find k.", "options": {"A": "4", "B": "5", "C": "6", "D": "7"}, "correct_answer": "C"},
    {"id": 92, "difficulty": "hard", "question": "Lines (a+1)x+2y=8 and 3x+by=12 are coincident. If a×b=15, find a,b.", "options": {"A": "a=3,b=5", "B": "a=5,b=3", "C": "a=2,b=7.5", "D": "a=4,b=3.75"}, "correct_answer": "B"},
    {"id": 93, "difficulty": "hard", "question": "For infinite solutions: px+qy=16 and 2x+4y=8. If p:q=1:2, find p,q.", "options": {"A": "p=2,q=4", "B": "p=4,q=8", "C": "p=6,q=12", "D": "p=8,q=16"}, "correct_answer": "A"},
    {"id": 94, "difficulty": "hard", "question": "Find k,m if kx+my=24 and 3x+4y=12 have infinite solutions and k-m=4.", "options": {"A": "k=8,m=4", "B": "k=10,m=6", "C": "k=12,m=8", "D": "k=14,m=10"}, "correct_answer": "C"},
    {"id": 95, "difficulty": "hard", "question": "System: (a-3)x+by=9, 2x+3y=6 has infinite solutions. If a+b=12, find a,b.", "options": {"A": "a=6,b=6", "B": "a=7,b=5", "C": "a=8,b=4", "D": "a=9,b=3"}, "correct_answer": "D"},
    {"id": 96, "difficulty": "hard", "question": "Lines (p+1)x+2y=10 and 4x+(q-2)y=20 coincide. If p=q, find p.", "options": {"A": "3", "B": "4", "C": "5", "D": "6"}, "correct_answer": "A"},
    {"id": 97, "difficulty": "hard", "question": "For infinite solutions: ax+3y=15, 2x+by=30. If a=2b, find a,b.", "options": {"A": "a=10,b=5", "B": "a=12,b=6", "C": "a=14,b=7", "D": "a=16,b=8"}, "correct_answer": "B"},
    {"id": 98, "difficulty": "hard", "question": "Find k,m such that kx+my=18 and 2x+3y=6 have infinite solutions and k/m=3.", "options": {"A": "k=12,m=4", "B": "k=15,m=5", "C": "k=18,m=6", "D": "k=21,m=7"}, "correct_answer": "C"},
    {"id": 99, "difficulty": "hard", "question": "System: (p-2)x+4y=8, 3x+(q+1)y=12 has infinite solutions. If p+q=10, find p,q.", "options": {"A": "p=4,q=6", "B": "p=5,q=5", "C": "p=6,q=4", "D": "p=7,q=3"}, "correct_answer": "C"},
    {"id": 100, "difficulty": "hard", "question": "Lines ax+2y=10 and 3x+by=15 are coincident. If a+b=13, find a,b.", "options": {"A": "a=6,b=7", "B": "a=7,b=6", "C": "a=8,b=5", "D": "a=9,b=4"}, "correct_answer": "A"}
  ]
}