PLS HELP!!!!
Determine the value of x.
A) 160°
B) 78°
C) 240°
D) 80°

Answer:
D) 80°
Step-by-step explanation:
(n - 2)180 = 4(180) = 720
78 + 134 + 136 + 132 + 2x + x = 720
3x + 480 = 720
3x = 240
x = 80