A and B can complete a work in 8 and 16 days respectively. A and B start working together and after 4 days, A left the work. Find in how many days work will be completed.

8

Total work = Efficiency × Number of days

Work done by ( A + B ) in 4 days = 3 x 4 = 12

Remaining work = 16 - 12 = 4 

Time taken by B to complete the remaining work = \(\frac{4}{1}\)

= 4

Total time taken in doing whole work = 4 + 4 = 8 days