Answer
$y=-1(x-4)$
Work Step by Step
The point-slope form of an equation of a non-vertical line with slope $m$ and through point $(x_1,y_1)$ is $y-y_1=m(x-x_1)$.
We plug in $4$ for $x_1$, $0$ for $y_1$, and $-1$ for $m$ to get the equation:
$y-0=-1(x-4)$
We simplify: $y=-1(x-4)$
