1. The problem asks to write the equation of the line shown in the graph in slope-intercept form $y=mx+b$. 2. From the graph, the line passes through the points $(0,160)$ and $(4,0)$. 3. The slope $m$ is calculated as the change in $y$ over the change in $x$: $$m=\frac{0-160}{4-0}=\frac{-160}{4}=-40$$ 4. The $y$-intercept $b$ is the value of $y$ when $x=0$, which is $160$. 5. Substitute $m=-40$ and $b=160$ into the slope-intercept form: $$y=-40x+160$$ 6. Therefore, the correct equation is option B: $y=-40x+160$.