When 2 parallel lines are intersected by a line, then most of the angles are congruent. you are given 106 for angle gha. So any angle that shares aside, you just subtract 180-106 to get that angle because together they equal 180. So by subtracting each angle you have from 180, you will get the angle.
1. 106
74
106
106
the total of the the 2 inside angles of the triangle equal the exterior angle, because it is just 180- the 2 angles inside.
2. 165
15
