I'm going to give you two ways to do this.
rise/run and m= (y2-y1)-(x2-x1)
First, let's try rise/run.
Pick two points on the graph. See how much they rise and they run. (go over)
I'm using (-3,0) and (0,3)
rise=3, run= 3
3/3= 1
Now, plug those into a slope formula.
m= (y2-y1)/(x2-x1)
m= (3-0)/ (0-(-3) Two negatives equal a positive.
m= 3/3 or 1
I hope this helped. I thought explaining two ways might make this easier.
~kaikers