Answer:
x = 80°
Step-by-step explanation:
Angle on a straight line = 180°
(x + 40)° + (x - 20)° = 180°
x + 40° + x - 20° = 180°
2x + 20° = 180°
2x = 180° - 20°
2x = 160°
x = 160°/2
x = 80°
Check:
(x + 40)° + (x - 20)° = 180°
(80° + 40°) + (80° - 20°) = 180°
120° + 60° = 180°
180° = 180°
