Answer
$y=2x-4$
Work Step by Step
The equation for a line defined by a point and a slope is $y-y_{1}=m(x-x_{1})$ in which $m$ is the slope, and $x_{1}$ and $y_{1}$ are the coordinates of a given point, so therefore...
$y-(-4)=2(x-0)$
$y+4=2x$
$y=2x-4$
