Question

Twelve farmers can harvest 2 hectares of rice in 3 days. How many farmers will it take to harvest 5 hectares in 10 days?

Answer 1

12 farmers * 3 days = 2 hectares

multiply by 5/2 and you have

12(5/2) farmers * 3 days = 5 hectares
Now on the left, multiply by (3/10)(10/3):

12(5/2)(3/10) farmers * 3(10/3) days = 5 hectares
9 farmers * 10 days = 5 hectares

or

12f * 3d = 2h
9f * 4d = 2h
9f * 10d = 2(5/2) = 5h