Slope is rise divided by run, or rise over run.
Look at a point on the graph, for example, (0, -4).
How much do you need to go up and then right to get to the next point?
If you go up 1 and right 1, you get to point (1, -3) which is also on the graph.
Going up 1 is a rise of 1.
Going right 1 is a run of 1.
Slope = rise/run = 1/1 = 1
