Step-by-step explanation:
for 2 lines to be parallel they must have the same angles with a crossing third line.
and it is a given for 2 crossing lines that the
top right angle = bottom left angle
top left angle = bottom right angle
it is also clear that the sum of all angles around a single point in one side of a line must be 180° (as the line is the diameter of a potential circle with the single point being the center of that circle, and so one side of the line represents a half-circle = 180°).
7.
angle 3 plus angle 8 are together 180°.
66 + 2x + 8 = 180
2x + 8 = 114
2x = 106
x = 53
8.
3x + 48 = 6x
48 = 3x
x = 16
