The two legs of a right triangle are 20 and x - 8, and the hypotenuse is x. find the length of the hypotenuse.

20^2 + (x-8)^2 = x^2

x^2 = 400 + x^2 -16x + 64

16x = 464

x = 29 = hypotenuse

Double - Check
29^2 = 20^2 + 21^2
841 = 400 + 441