It depends on how it's used.
For example if it's angles it could be because of Vertical Angles.
If it's Triangles it could be Definition of Congruent Triangles.
Your answer would be A:x=3
Answer:
Step-by-step explanation:
E
Answer:
1. 2x + 30° = 180°
2x = 150°
x = 75°
2. (2x - 24)° + (x + 12)° + (x - 8)° = 180°
4x - 20 = 180°
4x = 200
x = 50°