Vertical Angles Theorem: angles that are opposite each other and formed by two intersecting straight lines, are congruent.
6x - 7 = 4x + 7
2x = 14
x = 7
Or you can also do supplementary angles
6x - 7 + 20x + 5 = 180
26x - 2 = 180
26x = 182
x = 7
The answer is x = 7
