Multiple choice

A certain number of men can finish a piece of work in 20 days. If however there were 20 men less it will take 20 days more for the work to be finished. How many men were there originally?

  1. 20

  2. 40

  3. 80

  4. 30
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let x be the number of men. Work = x * 20. If men = x - 20, time = 40 days. Work = (x - 20) * 40. Equating: 20x = 40x - 800. 20x = 800, so x = 40.

AI explanation

Let the original number of men be M. The total work remains constant, so M multiplied by 20 days equals (M - 20) multiplied by 40 days. Expanding this gives 20M equals 40M minus 800, which simplifies to 20M equals 800. Therefore, the original number of men was 40.

Keep practicing — related questions