A and B can complete a work in 18 and 30 days respectively. A and B start working together and after 5 days, B left the work. Find in how many days work will be completed.

15

Total work = Efficiency × Number of days

Work done by ( A + B ) in 5 days = 8 x 5 = 40

Remaining work = 90 - 40 = 50

Time taken by A to complete the remaining work = \(\frac{50}{5}\)

= 10

Total time taken in doing whole work = 5 + 10 = 15 days