Question

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

Answer 1

In 60 days A alone can finish the work

Answer 2

A and B together finishes the whole work in 30 days


so in 20 days they together completes 2/3 of work

so 1/3 of whole work is remain

this work completes by A alone in 20 days after leaving B

so to complete 1/3 of whole work A needs 20 days


1/3 of work ----------- 20 days

1 full work --------- ??

days to complete full work = 20 × 3 = 60 days