A can complete a piece of work alone in 20 days, while B can do it alone in 30 days. They worked together for 5 days and left. The rest of the work is completed by C alone in 7 days. In what ratio should the payment be divided among them?

Let the total work be 60 units (LCM of 20 and 30) ⇒ Efficiency of A = 60/20 = 3 units/day ⇒ Efficiency of B = 60/30 = 2 units/day Combined efficiency of A and B = 3 + 2 = 5 units/day Work done by A and B in 5 days = 5 × 5 = 25 units Remaining work = 60 - 25 = 35 units Efficiency of C = 35/7 = 5 units/day Ratio of work done by A : B : C = Efficiency × time done by each Ratio of work done by A : B : C = 3×5 : 2×5 : 5×7 ⇒ Ratio of work done by A : B : C = 3 : 2 : 7 ∴ The payment is divided among A, B, and C in the ratio 3 : 2 : 7.