-5/2
To find the slope you need to use rise/run which is basically difference of y coordinates over difference of x coordinates
so first, pick 2 coordinates that you know in that linear relationship like in this case
(0,3) and (2,-2)
do rise/run which will look like this
=(y2-y1)/(x2-x1)
=(3-(-2))/(0-2)
=-5/2