Question

In a camp ,there is a meal for 120 men or 200 children . if 150 children have taken the meal, how many men will be catered to with remaining meal

Answer 1

Let x = food or meal

Thus the share of each men is x/120.
And the share of each children in x/200.

It was said in the problem that 150 children took the meal, so the total meal taken by these children is number of children multiplied by the share of each:
150 * x/200 = 3x / 4 = 0.75x

There are x meals total, so the remaining is
x - 0.75x = 0.25x

Divide this by the share of each men to get the number of men that can consume the remaining meal:
0.25x / (x/120) = 30 men

hope this helps~ `u`