4024/21 Oct/Nov 2025, Question 13: Simultaneous equations
Cambridge O Level Mathematics 4024 · Paper 21 (Calculator) · Calculator · 3 marks
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The question, in short
Solve the pair of equations 2a + 5b = 1.5 and 3a − 10b = 42.5, showing working.
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Solution · 3 marks
- 1Multiply the first equation by 2: 4a + 10b = 3
- 2Add to 3a − 10b = 42.5: 7a = 45.5
- 3a = 6.5
- 42 × 6.5 + 5b = 1.5 → 5b = −11.5
- 5a = 6.5, b = −2.3
Answera = 6.5, b = −2.3
Stuck on a step? Read the free lesson: Simultaneous Equations by Elimination
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