I have to go to a few places but my friend needs help with this specific equation!
Thank you!
~Hocus Pocus

Answer:
Hello, this would be a vertical angle graph. Since this graph is a supplementary graph since it stretches about 180 degrees, you would take both 7x and x+20 and set it equal to 180 like this:
7x+x+20=180
Then, you combine the xs and you would get this:
8x+20=180
Then, subtract 20 from both sides like this:
8x=160
Lastly, you would divide 8 by both sides and get x which is:
x=20
Step-by-step explanation:
I hope this helped you!