Answer
Slope: not possible to evaluate
y-intercept: there is no y-intercept
Work Step by Step
In a linear equation $y=mx+b$, $m$ is the slope and $(0,b)$ the y-intercept. That is, the y-intercept is the point on the line when $x=0$
$x+4=0$
$x+4=0y$
$0y=1x+4~~~~$
In order to find the slope, we should divide both sides by $0$. In this case we would find that: $m=\frac{1}{0}$
Also,
$x+4=0$
$x=-4$
Slope: not possible to evaluate
y-intercept: it is a vertical line with $x=-4$. That is, there no point on the line when $x=0$
