Because m and n are parallel, we can use the supplementary angles theorem. This means that the two angles add up to equal 180°.
Knowing this, we can add the two angles together and they should equal 180:
(3x + 5) + (x - 25) = 180
4x - 20 = 160
4x = 160
x = 40
If needed, to find the angle measures, we can just plug in our x value to find the measures of the angles.
