x will have a value of 20, which gives the angles a value of 90 degrees each.
Since they are alternating interior angles of a parallel lines, cut by a transversal, they are congruent. Therefore, you can set them equal to each other and solve for x.
5x - 10 = 4x + 10
x - 10 = 10
x = 20
Now that we have this, we can plug into either to find the angle measurements.
4x + 10
4(20) + 10
80 + 10
90
