Explanation:
A. Theta + 180 (when angle is less than 180)
Theta - 180(when angle is greater than 180)
Thus, 171 + 180 = 351°
B. I. Angle CBF + Angle BFG = 180 (Co interior angles)
CBF + 118 = 180
CBF + 118 –118 = 180 –118
CBF = 62°
Ii. 83 + X + CBF = 180 (Angles on a straight line)
83+X+62 =180
145+x=180
145–145+x=180–145
X = 35°