-x - y = 8
y = -x - 8 --- (1)
x - 3y = 8
3y = x - 8
y = (1/3)x - (8/3) --- (2)
Now, you just need to graph (1) and (2).
You will need to find two points on wach of them before you can graph them out.
Note that ANY two random points will do.
For example, for y = -x - 8, when x = 1, y = -9 and when x = 2, y = -10
This means (1, -9) and (2, -10) are on y = -x - 8
Thus, you just need to plot these two points, and draw a line through them, and you will get y = -x - 8
The same goes for y = (1/3)x - (8/3).
When x = 2, y = -2, and when x = 5, y = -1
Thus, (2, -2) and (5, -1) are two points on the graph.
We just draw a straight line through these two points and we will have the graph of y = (1/3)x - (8/3).
Note that the point of intersection between the two lines will be your solution to the system of equations. That point should be (-4, -4).