A, B and C can do a work in 12, 15 and 20 days respectively. In how many days, working together they can complete the same work?

5 days 4 days 7.5 days 6 days

5 days

A = 12 days, B = 15 days, C = 20 days, ⇒ Time required by A + B + C to complete the work = \(\frac{60}{5+4+3}\) = \(\frac{60}{12}\) = 5 days.     ..(\(\frac{Work}{Efficiency}\) = Time)