A and B can do a piece of work in 18 and 36 days, respectively. They start working together but A leaves after 3 days. How much time will B take to complete the remaining work?

Correct option is D

Total Work = LCM of 18 and 36 = 36 unit

Efficiency of A and B are$$\frac{36}{18}= 2$$ and $$\frac{36}{36}= 1$$ unit per day respectively.

Work done by A and B together in 3 days = (2+1)$$\times3= 9$$ unit

Remaining work = 36-9 = 27 unit

Remaining work done by B in $$\frac{27}{1}= 27 days$$​​