Explanation:
Corresponding angles formed by two parallel lines and a transversal are congruent.
The indicated angles are corresponding angles, therefore their measures are equal:
[tex]x+9=2x-111[/tex]
Solving for x:
[tex]\begin{gathered} x+9-x=2x-x-111 \\ 9=x-111 \\ x=9+111=120 \end{gathered}[/tex]
Answer:
x = 120º
