Question

A and B can together finish a work in 30 days. They worked at it for 20days and then B left. The remaining work was done by A alone in 20more days. A alone can finish the work in?

Answer 1

Amount of work done in 1 day = 1/30

Amount of work done in 20 days = 20 * (1/30) = 2/3
 
Remaining work = 1 - 2/3 = 1/3

Given, A completes 1/3 work in 20 days.

Therefore, A can finish the whole work in (20 x 3) = 60 days.


Hope this helps!

Answer 2

Work done by both A and B in 1 day=1/30
Work done by both in 20 days=20* 1/30
=20/30=2/3
Work remaining=1-2/3
=1/3
A completes 1/3 work in 20 days,
A will complete the whole work in ?
Work done by A in one day = 1/3 * 1/20 = 1/60
Thus A will complete the work in 60 days