A B together can do a work in 8days .If A alone can do the same work in 12 days then the number of days in which B alone can finish the same work is......
SInce work done is inversely proportional to work done,
1/AB =1/A + 1/B
1/8 = 1/12 + 1/B
1/B = 1/8-1/12
1/B = 1/24
So, time taken by B = 24 days