Answer:
x = 10
Step-by-step explanation:
Adjacent angles add to 180 degrees, so set the angles equal to 180
(7x + 12) + (9x + 8) = 180
- 12 - 12
7x + (9x + 8) = 168
- 8 - 8
7x + 9x = 160
16x = 160
/16 /16
7x + 12 + 9x + 8 = 180
16x + 20 = 180
