Question

A and b can do a piece of work in 45 days and 40 days respectively. they began to do the work together but a leaves after some days and then b completed the remaining work in 23 days. the number of days after which a left the work was time and work

Answer 1

I hope that you understand...
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Answer 2

Here is your answer.

A can do a piece of work in 45 days.
B can do a piece of work in 40 days.
So, Work done by B in 23 days = 23/40 .
Remaining work = 1-23/40 = 17/40.
that means, 17/40 work is done by both A and B.
Now, Work done by both in one day =
1/40 + 1/45 = 85/40*45.
So, 17/40 work will be done in 40*45/85 * 17/40 = 9 days .