Answer
Slope $m=0$ and y-intercept $b=8$.
Work Step by Step
The slope-intercept form is
$y=mx+b$ where $m$ is the slope and $b$ is the y-intercept.
Given: $y=8$ which can be written as $y=0x+8$.
Comparing with the slope-intercept form, we get
$m=0$ and $b=8$.