Answer:
y=140°
Step-by-step explanation:
Method 1.
The exterior angle theorem tells us that y=20+120=140
Method 2.
Solve for x first., then use that to solve for y.
The sum of the interior angles of a triangle is 180, so we can get x by doing 180-20-120=40.
y and x make a straight angle which is 180°, so we can get y by doing 180-40=140
