70 men dig 15,000 sq. m of a field in 5 days
1 men can dig 15,000 sq. m of a field in = (5 × 70)/15,000
Men required to dig 22,500 sq. m field in 25 days = (5 × 70 × 22500)/(15,000 × 25) = (70 × 900)/3000 = 63/3 = 21
Hence required to dig 22,500 sq. m field in 25 days = 21