A and B can complete a work in 20 days. If A alone can complete the work in 30 days, how long will B

A. 15 days

B. 25 days

C. 40 days

D. 60 days

E. None of the above

Answer: C. 40 days

Let B's time to complete the work be x days. The equation is 1/30 + 1/x = 1/20. Solving gives x = 40 days.

Posted in: Time & Work - Aptitude - Mathematics