The angles below are supplementary. what is the value of x?

a pair of supplementary angles is shown. one angle measures 8x plus 60 degrees, and the other angle measures 80 degrees.

5
17.5
20
40

If you need the answer quickly, just scroll to the bottom. 
If you need the explanation, Read it all.(Lol)

So, we know that the two angles must add up to 180. So, we have the equation:
8x + 60 + 80 = 180. 
So, We first need to subtract 60 From 180 to start the simplifying. 
180-60 = 120
The somewhat simplified version is:
8x + 80 = 120
Next, subtract the 80.
120-80 = 40.
The Almost Done Version Is :
8x = 40
No, we need to solve for x. We must first Divide both sides by 8 to get the x alone.
8x/8 = 1x = x
So:
X = 40/8
40/8 = 5.
So:
X = 5
I hope this explanation helps.

3x+9+4x+x=8x+9that's the answer for your question.