A can do a piece of work in 24 days. If B is 60% more efficient then the number of days required by B to do the twice as large as the earlier work is-
A works twice as fast as B. If both of them can together finish a piece of work in 12 days, then B alone can do it in
(a) 24 days
(b) 27 days
(c) 36 days
(d) 48 days