John’s tent has slanted sides that are each 5 feet long with a bottom 6 feet across. what is the height of his tent at the tallest point? a) 3.0 ft b) 3.5 ft c) 4.0 ft d) 5.0 ft

The answer is, "c","4.0 ft".
if we draw a line at center, now it makes two triangles and the total length of the bottom is 6, so split that in half, which is 3.
Now, by using Pythagorean theorem, a² + b² = c²
Now b = 3 and given that c = 5
a² + 3² = 5²
a² = 25 - 9
a² = 16
a = 4
Thus, the height of his tent at the tallest point is 4 ft.

Yes. Juan will break even because 16 and -16 are a zero pair. -16 is the additive inverse of 16. So the sum will be 0.