Answer: 15
Step-by-step explanation:
Pythagorean theorem: c^2 = a^2 + b^2 where c is hypotenuse, a and b are legs.
In this problem:
a = 20
c = 25
b - ?
b^2 = c^2 - a^2
b^2 = 25^2 - 20^2
b^2 = 625 - 400
b^2 = 225
b = sqrt(225)
b = 15
