Multiple choice

A can finish a work in 20 days and B can finish the same work in 25 days. They began together, but B left the work after 5 days. How many more days will A take to finish the remaining work?

  1. 11

  2. 8

  3. 16

  4. 21
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A's work rate = 1/20 per day. B's work rate = 1/25 per day. Combined rate = 1/20 + 1/25 = 9/100 per day. In 5 days together, they complete 5 × 9/100 = 45/100 = 9/20 of the work. Remaining work = 11/20. A alone needs (11/20) ÷ (1/20) = 11 more days to finish.

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