Explanation

To find how many more men are needed, we can use the formula for work:

$$text{Work} = text{Men} times text{Days}$$

Initially, 120 men can complete the work in 90 days. The total work can be represented as:

$$120 times 90 = 10800 text{ man-days}$$

Now, we need to find how many men are needed to complete the work in 40 days:

$$text{Required Men} = frac{10800}{40} = 270 text{ men}$$