Answer is slope of 2/3
The quickest way is to find rise over run on your graph, see attached. Remember y over x is slope.
Otherwise you can find two points on the graph, use formula (y2 - y1) over (x2 over x1)
(0, -3) and (3, -1)
-1 - -3 over 3 - 0
2 over 3 = 2/3