Let’s start by using the formula:

number of men × number of days = constant

We can use this formula to find the constant, which represents the total amount of work to be done:

15 men × 10 days = constant

150 = constant

Now we can use the constant to find the number of men needed to do the same job in 3 days:

number of men × 3 days = 150

number of men = 150 ÷ 3

number of men = 50

Therefore, we need 50 men to do the same job in 3 days. To find how many more men are required, we can subtract the initial number of men from the new number of men:

50 men – 15 men = 35 more men are required.