Numerical answer
A can complete a piece of work in 12 days and B can complete it in 18 days. They start working together, but A leaves 3 days before the work is finished. In how many days is the total work completed?
Show answer and solution
Answer: 9
Let the total time taken be x days. A works for (x−3) days and B works for all x days. Work done: (x−3)/12 + x/18 = 1. Multiplying through by 36: 3(x−3) + 2x = 36 → 3x−9+2x = 36 → 5x = 45 → x = 9. Check: A works 6 days → 6/12 = 1/2; B works 9 days → 9/18 = 1/2; total = 1. Correct.
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