Help
I’ve tried many times , answer ended up wrong .

Step-by-step explanation:
[tex] {15}^{2} = {12}^{2} + {x }^{2} \\ 255 - 144 = {x}^{2} \\ 81 = {x}^{2} \\ \sqrt{81 } = x \\ 9 = x[/tex]