SOLUTION
Given the question in the image, the following are the solution steps to verify the identity
STEP 1: Write the given identity

STEP 2: Verify the identity

The verification of the identity is as seen above.
Answer:
C 120
Step-by-step explanation:
Answer:
angle 2 = 90° {corresponding angles}
angle 7 + angle 5 = 180° {linear pair}
or, angle 7 + 100° = 180° {angle 5 is corresponding to 100°}
so, angle 7 = 80°
I feel like it’s B but I’m not sure