To find slope, we must find the change in y values divided by the change in x values, also called the rise/run. This is modeled below:
Slope = m = (y1 - y2)/(x1-x2) = (6-(-3))/(1 - (-6)) = (6+3)/(1+6) = 9/7
We can check that this answer is correct by consulting the graph. The graph shows a positive correlation (means that the slope should be positive), and if you count the graph unit squares, you get that the graph moves up 9 squares and over 7 squares between the two points shown, letting us know we got the right answer.
Hope this helps!