Explanation:
the law of intersecting lines : the angles between both lines are the same on both sides of either line, just left-right mirrored.
that's why the angles are while going around the intersection point (starting with the known 37° angle) :
37° - supplementary angle - 37° - supplementary angle
and again from the start.
"supplementary" angles are pairs of angles that together are 180°. just like 2 neighboring angles at intersecting lines.
so, 37° = 7x - 5
example 4
116° is the supplementary angle of 4x.
that means
180 = 116 + 4x
64 = 4x
x = 64/4 = 16