A can complete a piece of work in 20 days and B in 30 days. They work together for 5 days, and then A leaves. How many days will B take to finish the remaining work?

Explanation

A’s 1-day work = 1/20, B’s 1-day work = 1/30. Combined 1-day work = 1/20 + 1/30 = 5/60 = 1/12. In 5 days, they complete 5/12 of the work. Remaining work = 7/12. Time taken by B = (7/12) / (1/30) = (7 * 30) / 12 = 17.5 days.