Answer:
x = 2
Step-by-step explanation:
The two angles are congruent because they are alternative interior angles.
9x + 4 = 3x + 16
9x - 3x + 4 = 3x - 3x + 16
6x + 4 = 16
6x + 4 - 4 = 16 - 4
6x = 12