Answer
$y=-1/4x+2.25$
Work Step by Step
We first find the slope. The equation for slope is: $ \frac{y_{2}-y_{1}}{x_{2}-x_{1}}$. Thus, we obtain:
$\frac{2-3}{1-(-3)}=\frac{-1}{4}=-1/4$
We now plug this slope in for m, plug in an (x,y) point on the graph, and solve for b:
$y=-1/4x+b \\\\ 3=-1/4(-3)+b \\\\ b=2.25$
We now plug b in with m to get the final equation:
$y=-1/4x+2.25$