Let the efficiency of one man be M and of one B According to the question, (2M + 3B) 10 = (3M + 2B) 8 ⇒ 20 M + 30 B = 24 M + 16 B ⇒ 14 B = 4 M or 2 M = 7 B or We can say 10 boys can complete the work Now, time taken to complete the work by 2 men and 1 boy = time taken to complete the work by 8 boys. Now, 10 boys can do work in 10 days ∴ 8 boys can do it in