Find two points on the line to use.
I'll use ( -8,-5) and (0,-3)
Slope = change in Y over change in x:
Slope = (-3 - -5) / 0- -8 = 2/8 = 1/4
Now use the point slope form y-y1 = m(x-x1)
y - (-5) = 1/4(x-(-8))
y +5 = 1/4(x +8)
Now write in slope intercept form y = mx+b
Simplify 1/4(x+8) = x/4 +2
y +5 = x/4 +2
Simplify to get y = 1/4x -3