Question

X and Y =?

(Diagram included in the comments)

Answer 1

use pythagoras thorem for x

Answer 2

I did that. It didn't work

Answer 3

It works. To show you an example, I will do x for you.
By applying Pythagoras' Theorem, \(8^2 + x^2 = 10^2\). By solving this, you get \(x^2 = 36\). Now square root both sides, and you get x = 6.
Hint: the expression for y is \(9^2 + 12^2 = (y + 8)^2\). Note that at no point are you required to expand \(y + 8\) - Just solve the left hand part first and square root both sides.