What have you done so far? Where are you stuck?
Pick a few values of x and y, and see where they are on the graph.
For instance, where x = 0, we get:
8y + 7x = 8
8y + 7(0) = 8
8y + 0 = 8
8y = 8
(8y)/8 = 8/8
y = 1
Now, plot this point on the graph.
Try again for at least 3 or 4 values of x that are positive, and 3 or 4 values that are negative.
Do enough that you can see the pattern.
After you see a pattern, try a few more to make sure you understand it.