A and B can do a piece of work in 25 hours and 30 hours respectively. They began to do the work together but A leaves after some hours and then B completes the remaining work in 18 hours. The number of hours after which A left the work was?
60/11
(A + B)'s 1 hour's work = (125+130) = 11150
Work done by B in 18 hours = (130 × 18) = 35.
Remaining work = (1−35) = 25
Now, 11150 work was done by (A + B) in 1 hour
25 work done by (A + B) in (15011 × 25) = 6011 hours
A left after 5511 hours.