The angles are complementary meaning they =90 degrees.
So take (x-20) and x, and write this equation,
x-20+x=90
2x-20=90
move the 20 over
2x-20=90
+20 +20
2x=110
x=55.
You can check it by plugging it back in,
(55-20)=35
and
x=55
35+55=90.
Thus, you know your answer is correct.
