A and B can together complete a piece of work in 18 days, B and C can together complete the same work in 24 days and A and C can together complete it in 36 days. In how many days can A, B and C, working together, complete this piece of work?

16

A + B = 18 days,

B + C = 24 days,

A + C = 36 days,

⇒ Adding all the efficiencies =  2(A + B + C) = 9

⇒ A + B + C = \(\frac{9}{2}\) 

Time required by A + B + C to complete the total work = \(\frac{72 × 2}{9}\) = 16 days.     ..(\(\frac{Work}{Efficiency}\) = Time)