Answer:
x = 30, y = 90
Explanation:
Vertical angles (angles on opposite sides of intersecting lines) are congruent.
2x = y − x
Supplementary angles add up to 180°.
2x + y + x = 180
Solve the system of equations. Using substitution:
y = 3x
2x + 3x + x = 180
6x = 180
x = 30
y = 90
Alternatively, you can say (y+x) and (y−x) are also supplementary:
y + x + y − x = 180
2y = 180
y = 90
Then use vertical angles to show x = 30.