Answer
$y=-4x+8$
See graph.
Work Step by Step
Step 1. Using $x=r\ cos\theta$ and $y=r\ sin\theta$, we have $4x+y=8$ or $y=-4x+8$
Step 2. We can identify the above equation as a line with slope $-4$ and y-intercept $8$.
Step 3. See graph.