Multiple choice

A can do a work in 27 days while B takes 45 days to do the same work. They start working together, but A leaves 9 days before the work is over. How many days does A work?

  1. 18

  2. 27

  3. 13.5

  4. 27.5
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A's 1 day work = 1/27, B's 1 day work = 1/45. Let total days = d. A works for (d-9) days, B works for d days. (d-9)/27 + d/45 = 1. Multiply by 135: 5(d-9) + 3d = 135, so 8d - 45 = 135, 8d = 180, d = 22.5. A works for 22.5 - 9 = 13.5 days.

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