Answer: D. 90
Step-by-step explanation:
We can first determine that the angle measures are x, 40, and 50. (We can determine 50 by subtracting 130 from 180.) So, we can set up the equation
x + 40 + 50 = 180 because there are 180 degrees in a triangle.
Solve by combining like terms then subtracting.
x + 90 = 180
x = 90
