Explanation:
so in a 4 sided figure all the angles measure to 360º in total
as well as in this case due to the two lines being parallel z=x+60 and y=2x
The easiest way for me is to write that all the angles = 360.
x+60+x+60+2x=2x=360
6x+120=300 simplify
6x=180 divide
x=30
so the angles are all 90º if you find each of them