Help me please ASAP!!!!

Answer:
x= 20
Step-by-step explanation:
Considering this is a strait line, when you add both of these angles, you should get 180. To check my work:
(3x+8) plug in the 20 so it is 3(20)+8 = 68
(5x+12) plug in the 20 so it is 5(20)+12= 112
Then you simply add 68 and 112 which gets you 180. Meaning, x=20
Hope this helped :)