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 . after how many days did a leave the job?

Answer 1

A can finish the work in 45days
B '' '' '' '' '' 40days
In one day A can do 1/45parts of work
'' '' '' B '' '' 1/40parts of work
'' '' '' A&B together can do
1/45+1/40=8/360+9/360=17/360parts of work
B did 23 days alone
Part of work done=23*1/40=23/40
Part of wok done before A left=1-23/40=17/40
Therefore no. of days worked together =
(17/40)/(17/360)=360/40=9
Hence A left after 9 days