Question

A and B together can finish a piece of work in 12 days. If A alone can finish the same work in 20 days, In how many days B alone can finish it?

Answer 1

a+b one day work=1/12
a one day work=1/20
b one day work =a+b-b
=1/12-1/20
=8/240=1/30
b can do work in 30 days