Question

Because angle 2 is 120 degrees, angle DEG must also be 120 degrees because:

Answer 1

1. A straight line measures 180 degrees.
2. Angle 2 and angle DEG are on a straight line.
3. Angle 2 measures 120 degrees, so the remaining measure to complete the straight line is 60 degrees.
4. Therefore, angle DEG must measure 60 degrees to complete the 180-degree straight line.