Since the "x" values are vertical angles, and so are the "y" values, you must make them equal. If this is confusing, look at steps below (The order of solving the "x" or "y" values don't matter. I will write both ways down (in point form -->
and as just "x=..." "y=..."
First step is to make the "y" values equal each other
Next to solve make the "x" values equal each other
Final Answer:
x = 11; y = 17
Hope this helps :)