Answer:
C. 132°
Explanation:
Based on exterior angle theorem,
(20x + 12) = (9x) + (13x)
Solve for x
20x + 12 = 9x + 13x
20x + 12 = 22x
Subtract 20x from each side
12 = 22x - 20x
12 = 2x
Divide both sides by 2
12/2 = x
x = 6
m<QRS = 20x + 12
Plug in the value of x
m<QRS = 20(6) + 12 = 120 + 12
m<QRS = 132°