∠4 = 11
Explanation:
In this question we can use the exterior angle theorem. This means that the two other angles that aren't adjacent to ∠4 are equal to ∠4 when added together. If you add ∠1 and ∠2 together, you will get ∠4.

Combine like terms.

Subtract 13x from both sides.

Subtract 12 from both sides.
∠4 = 11