Apainter leans a 25-ft ladder against a building. the base of the ladder is 7 ft from the building. to the nearest foot, how high on the building does the ladder reach?

The easiest way to solve this problem would be to use the pythagorean theorem. Plug in the information you know. 25 will have to be c because it is the hypotenuse. You can plug 7 in for a or b. It does not matter which one you plug 7 in for because you will still get the same answer. 

This is what it should look like:
7^2 + b^2 = 25^2

Now solve the equation. 
7^2 = 49
25^2 = 625

The new equation will be 49 + b^2 = 625

Now subtract 49 from 625. 

625 - 49 = 576

b^2 = 576

Now take the square root of both sides to get b by itself. 

b = 24

Your answer should be: The ladder reaches 24 ft. high on the building.