Answer:
x = 34
Explanation:
139° is an exterior angle of the triangle shown in the diagram.
77° and (2x - 6)° are opposite interior angles of the triangle.
Based on the external angle theorem,
77° + (2x - 6)° = 139°
Solve for x
77 + 2x - 6 = 139
71 + 2x = 139
Subtract 71 from each side
2x = 139 - 71
2x = 68
Divide both sides by 2
x = 68/2
x = 34