A and B together can do a piece of work in 24 days. A alone can do this work in 40 days. In how many days can B alone do this work?

60 days

A + B = 24 days, A = 40 days,

⇒ A + B = 5   (Efficiency)

⇒ 3 + B = 5,

⇒ B = 2,

⇒ Therefore, time required for B to complete total work is = \(\frac{120}{2}\) = 60 days.   ..(\(\frac{Work}{Efficiency}\) = Time)