what does x = ? need help with the pythagorean theorem

Answer:
The answer is 9
Step-by-step explanation:
set up the equation as 12^2 + b^2 = 15^2
solve the exponents and you get 144 + b^2 = 225
Then subtract 144 from both sides and get 81
After that just do the square root of 81 and you get 9
pls mark brainliest