Answer
$y = \frac{-1}{2} x + 4$
Work Step by Step
From the graph, we are given the points $(0,4) (8,0)$
To determine the slope, use $m = \frac{y_{2}-y_{1}}{x_{2}-x_{1}}$
Using (0,4) and (8,0), $m = \frac{0-4}{8-0} = \frac{-4}{8} = \frac{-1}{2}$
b (the y-intercept) is equal to 4 (from (0, 4))
Thus the equation is $y = \frac{-1}{2} x + 4$