Answer:
C
Step-by-step explanation:
The sum of the angles is 360; n represents number of sides
S = (n - 2) x 180
S = (4-2) x 180
S = 2 x 180
S = 360
Setup the equation and simplify
2x + 10 + x - 20 + x + 40 + x = 360
5x +30 = 360
5x +30 - 30 = 360 - 30
5x = 330
5x/5 = 330/5
x = 66
