42 men can do a piece of work in 18 days. How many men would be engaged to do the same work in 21 days?
Answer: (1) 36
M1D1 = M2D2
where, M = number of men
D = number of day
According to question, 42 x 18 = M2 x 21
M2 = 42 x 18 /21 = 2 x 18
= 36 men
Hence, 36 men would be engaged to do the same work in 21 days.