Let total amount of work be 160 units Efficiency of ‘A’ = 160/20 = 8 units/day Efficiency of ‘B’ = 160/32 = 5 units/day Amount of work done by ‘A’ and ‘B’ together in 5 days = (8 + 5) × 5 = 65 units Time taken by B to complete remaining work = (160 – 65)/5 = 19 days