A work-force of 420 men with a contractor can finish a certain piece of work in 9 months. How many extra men must he employ to complete the job in 7 months?
Let the number of men required is 
Men | 420 |
|
Time (months) | 9 | 7 |
Therefore the number of extra men required to complete the work = 540 – 420 = 120 Men
7