Given the Right Triangle, you can identify that has two equal sides. Therefore, you can determine that it is a Right Isosceles Triangle.
By definition, a Right Isosceles Triangle has two equal sides and two equal angles, and the third angle measures 90 degrees (also called "Right Angle").
Therefore, you can determine that, in this case:

By definition, the sum of the interior angles of a triangle is 180 degrees. Then, knowing that a Right Isosceles Triangle has two equal angles and another angle that measures 90 degrees, you can set up this equation:


(Since "y" and "x" have the same measure, you can rewrite the equation using any of them, as you can see above)
Solving for "x", you get:



Hence, the answer is:

