Question on Finding unknown value in a Geometrical Figure

Topic : Internal Opposite Angles are Equal

Question : Find the unknown angle in the geometrical figure.

Solution :

Line L is parallel to line M
N is the traversal

5x – 28 = 3x + 12
5x - 3x -28 = + 12

->2x - 28 = + 12
-> 2x – 28 +28 = +12 +28 (adding +28 on both sides)

-> 2x/2 = +40/2 (dividing both sides by 2)
-> x = 20