∠1 = 100° (option E)
Explanation:
∠5 and 80 degrees are supplementary angles.
Their sum is equal to 180 degrees
∠5 + 80° = 180° (sum of angles on a line)
∠5 = 180 - 80
∠5 = 100°
The angle at the top of the first line corresponds to the the angle at the top of the 2nd line
∠5 corresponds to ∠1
Corresponding angles are equal
∠5 = ∠1
Hence, ∠1 = 100° (option E)
