The answer is x = 3. I hope this helped
True got it right in edge 2020
Hello!

Use the Pythagorean Theorem to solve for x:
a² + b² = c²
We are given the lengths of two sides, so we can plug those into the formula:
9² + 12² = x²
81 + 144 = x²
225 = x²
√225 = x
x = 15.