please help me! i'm stuck on it

Answer:
x = 15.4
Step-by-step explanation:
Because this is a right triangle, you can use the pythagorean theorem to find the length of the hypotenuse. the theorem is a^2 + b^2 = c^2
so
9^2 + 12.5^2 = c^2
solving this will give you 15.4