Answer:
55°
Step-by-step explanation:
2x + 1 + x - 7 = 180° Straight angle
3x - 6 = 180°
3x = 180 + 6 = 186
3x = 186° Divide both sides by 3
x = 62°
Angle ADC = x - 7 Vertically opposite angles
Angle ADC = 62° - 7°
Angle ADC = 55°
