If 18 men can cut a field in 35 days, then in how many days can 21 men cut the same field ?

27 28 30 32

30

Formula to be used here; \( { M}_{1 } \) x \( { D}_{1 } \)  = \( { M}_{2 } \) x \( { D}_{2 } \) where, M = No. of men, D = No. of days, ⇒ Putting in the values, ⇒ 18 x 35 = 21 x \( { D}_{2 } \) ⇒ \( { D}_{2 } \) = 30 days.