Answer:
x = 20
Step-by-step explanation:
To do this question, you can use the pythagorean theorem. c is your hypotenuse, a is the unknown side length and b is the known side length.
a^2+b^2=c^2
x^2+15^2=25^2
x^2=225=625
x^2=400
(x^2)^(1/2)=400^(1/2)
x = 20
