Time taken by 15 men working 8 hours a day = 10 days Time taken by 1 man working 1 hour a day = 10 × 15 × 8 Time taken by 6 men working 20 hours a day =
10×15×8
6×20
= 10 days. So, 6 men working 20 hours a day can accomplish the given assignment in 10 days.