Hi there!
To start, we can use the two points to find the slope using the formula y2-y1/x2-x1. Just sub in the points and solve!
-0.5-0.5/3-(-3)
-1/6
Sub that into the formula y-mx+b for m, and use one of the points for x and y - solve for b and you get your equation.
y=mx+b
y=-1/6x+b
0.5=-1/6*-3+b
0.5=-0.5+b
0.5+0.5=b
b=1
Therefore your equation is y=-1/6x+1
Hope this helps!