A and B can do a piece of work in 20 days and B in 15 days. They work together for 2 days and then A goes away. In how many days will B finish the remaining work?
Given,
A and B can do a piece of work in = 20 days
B can do it in = 15 days
∴ A and B’s 1 day work = 
B’s 1 day work = 
∵ A and B work for 2 days, hence work done by them in 2 days = 
Remaining work = 
∵ B do 
work in = 1 day
B do 1 complete work in = 
∴ B will do 
work in = 
days
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