Angles 2 and four are same side interior angles, then they are supplementary, that is,
∠2 + ∠4 = 180
Substituting with data:
(2x + 10)+ (4x + 80) = 180
Combining similar terms:
(2x + 4x) + (10 + 80) = 180
6x + 90 = 180
Substracting 90 at both sides:
6x + 90 - 90= 180 - 90
6x = 90
Dividing by 6 at both sides:
6x/6 = 90/6
x = 15
