- X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last?
(A) 6 days
(B) 10 days
(C) 15 days
(D) 20 days
(A) 6 days
(B) 10 days
(C) 15 days
(D) 20 days