GIVEN : A worked with B and C for the initial 3 days and then A left the work. 70% of the work is completed by B and C working together and total work is completed in 13 days. If C is 4/3 efficient than B. ASSUMPTION : Let, the total work be 100 units CALCULATION : Number of units completed by B and C working together = 70 units Number of units completed by A, B and C working together = 100 – 70 = 30 units Number of units completed by A, B and C working together in 1 day = 30/3 = 10 units Time taken to complete the whole work = 13 days ∴ Number of days B and C work together to complete the remaining work = 13 – 3 = 10 days ∴ Number of units completed by B and C work together in 1 day = 70/10 = 7 units ∴ Number of units completed by A alone in 1 day = 10 – 7 = 3 units ∵ C is 1/3rd more efficient than that of B ∴ Number of units completed by C alone in 1 day = 4 units ∴ Number of units completed by B and A work together in 1 day = 6 units Time taken by A and B to complete the work = 100/6 = 50/3 days