Respuesta :

Answer: x=3

Step-by-step explanation:

Use Pythagorean theorem.

a^2 +b^2 = c^2

4^2 +b^2 = 5^2

16 +b^2 =25

-16 from both sides

b^2 = 9

square root b^2 = square root 9

b = 3

b=x

x=3