use the appropriate theorem(s) to find the measure of ∠1. m∠1 = □°

use the appropriate theorem(s) to find the measure of ∠1. m∠1 = □°
Answer
Explanation:
Step1: Recall vertical - angles property
Vertical angles are equal.
Step2: Identify vertical - angle relationship
The angle given ($120^{\circ}$) and $\angle1$ are vertical angles.
Answer:
$120$