Answer:
C = 132
Step-by-step explanation:
The measure of the exterior angle of a triangle is equal to the sum of the opposite interior angles
20x+12 = 9x+13x
Combine like terms
20x+12 = 22x
Subtract 20x from each side
20x-20x+12 = 22x-20x
12 = 2x
Divide by 2
12/2 = 2x/2
6 =x
QRX = 20x+12
20*6 +12
120+12
132
