From the image provided, it shows that both 8x - 12 would equal 6x + 8 because their angles are the same due to their placement. With that it turns into 8x - 12 = 6x + 8. Then you can simplify to 2x = 20 by adding 12 to both sides, and subtracting 6x. Then 20 divided by 2 to get x by itself equaling 10.