A can complete a work in 20 days, B in 30 days. They work together for 5 days, then C completes the remaining work in 5 days. How long would C take to complete the whole work alone?
Q1. A can complete a work in 20 days, B in 30 days. They work together for 5 days, then C completes the remaining work in 5 days. How long would C take to complete the whole work alone?
Answer: 15 days
Explanation: A's 1 day work = 1 / 20, B's = 1 / 30. Together, 1 day work = 1 / 20 + 1 / 30 = (3 + 2) / 60 = 1 / 12.