Question

12 men can reap a field in 25 days. In how many days can 20 men reap the same field?

Answer 1

12 men can reap a field in 25 days.
1 man can reap a field in 25 × 12 days.
20 men can reap a field in $\frac{25\times 12}{20}=15$ days.

Hence, 20 men can reap the same field in 15 days.