If A can do a work in 24 days and B can do it in 36 days, how many days will it take for A and B to complete the work if A works alone for 10 days and then B joins him?
Answer: C. 18 days
A completes 10/24 of the work in 10 days. The remaining work is 14/24. A and B together can complete the work in 18 days.