A can finish a work in 12 days and B can finish it in 18 days. A works alone for 3 days and then B joins him. In how many more days will the work be completed?

Explanation

A’s 1-day work = 1/12, B’s 1-day work = 1/18. In 3 days, A completes 3/12 = 1/4 of the work. Remaining work = 3/4. Combined 1-day work = 1/12 + 1/18 = 5/36. Remaining days = (3/4) / (5/36) = 27/5 = 5.4 days.