Question

If a and b can do a piece of work in 10 days and a alone can do it in 15 days, how long will b take to do it?

Answer 1

(A+B)'s 1 day work= 1/10th part

A's 1 day work = 1/15th part

B's 1 day work = 1/10-1/15 = 1/30th part

B can alone do work in 30 days