The slope is -2/5.
I picked 2 points on the graph and found the slope using the slope formula.
y₂ - y₁ -4 - (-2) -4 + 2 -2
------------ = -------------- = ------------ = ------
x₂ - x₁ 5 - 0 5 5
You can also find slope by using rise/run:
1). Pick 2 points on a graph.
2). The goal is to connect those two points.
3). Count a certain amount of units up and across to get to your second point.
4). If your second point is negative, you have to count a certain amount of units down and across to reach your second point.
If my words don't make any sense, check out www.algebra-class.com. There is a full explanation of this.
I hope I could help you!