A and B can finish a work in 20 days. A alone can do 
th of the work in 12 days. In how many days can B alone do it?
Given,
A and B can finish a work in = 20 days
A can 
work in = 12 days
∴ A+ B ‘s 1 day work = 
∴ A’s 1 day work = 
B’s 1 day work = (A+B)’s 1 day work – A’s 1 day work
= 
Thus B can finish the work in = 
11