Answer:
x = 5
Explanation:
We need to remember that vertical angles are opposite to each other when two lines cross. The vertical angles that result from two lines crossing have the same measure.
In this problem we have angle E which measures 8x + 8 and angle F which measure 2x + 38.
Since they are vertical angles, we know that they have the same measure and therefore we can equal them both and solve for x:

Therefore, x = 5 (and ∠E = ∠F = 48)