Answer:
x = 20
∠B =150°
Step-by-step explanation:
Angles A and B are alternate interior angles formed by the intersection of a line with two parallel lines. Therefore, the measure of A and B is the same.

Now since ∠A = 8x - 10 and ∠B = 3x + 90, the above equality gives

We just need to solve for x.
Adding 10 to both sides of the equation gives
