Answer:
12
Explanation:
the angles on top of a line (or below a line) sum up to 180 degrees, as a line stands in that regard for a flip from left to right - which is a half circle or 180 degrees.
therefore, the sum of both angles must be 180.
10x - 20 + 6x + 8 = 180
16x -12 = 180
16x = 192
x = 12