Since angle A and B are interior angles, we can set them equal to each other. So then we can solve for x and plug x in for B.
1) 8x + 78 = 2x + 114
2) 8x - 2x = 114 - 78
3) 6x = 36
4) 6x / 6 = 36 / 6
5) x = 6
Now we can plug in x to equation b
1) 2(6) +114
2) angle b = 126
hope this helps :)
