Its a square pool and its perimeter is 100 yards.
We know that a square has 4 sides with the same length so we can give a square perimeter by the sum of their 4 sides
Lets call the side "l" and since we have 4 of them we need to sum it 4 times
l + l + l + l = perimeter
4l = perimeter
We know the perimeter
4l = 100
Divide both sides by 4
4l/4 = 100/4
l = 25
So the side length is equal to 25 yards
