Question

a can do a piece of work in 15 days and b alone can do it in 10 days.b works at it for 5 days and then leaves. a alone can finish the remaining work in?

Answer 1

10/5= Half of the work is left...
Therefore, (1/2)*15= 7 and a Half days more..

Answer 2

The answer is 10 or 5 days