5x - 30° = 3x + 30° ( unghiuri alterne externe)
5x - 3x = 30° + 30°
2x = 60°
x = 60° : 2
x = 30°
Răspuns:
5x-30°=3x+30°
5x-3x=30°+30°
2x=60°
x=30°
d)
