A man and a boy together can complete a job in 81 days. Two men and three boys together can complete the same job in 36 days. In how many days can four men together complete the same job?

Correct Answer: 27
Man = M , Boy = B1M + 1B = 1/8181M + 81B = 1 work2M + 3B = 1/3672M + 108B = 1 work81M + 81B = 72M + 81B9M = 27B 1M = 3B4M = 12B12B = 4/12 x 81 Days4M = 27 Days