Answer
$y$-intercept $=5$
Work Step by Step
Point on a line: $(3,-1)$ $;$ Line's slope: $-2$
Obtain the $y$-intercept. Do so by obtaining the line's equation.
The point-slope form of the equation of a line is $y-y_{1}=m(x-x_{1})$, where $m$ is the slope of the line and $(x_{1},y_{1})$ is a point through which it passes.
Both $m$ and $(x_{1},y_{1})$ are given, so substitute them into the point-slope form of the equation of a line formula and simplify:
$y-y_{1}=m(x-x_{1})$
$y-(-1)=-2(x-3)$
$y+1=-2x+6$
Solve for $y$:
$y=-2x+6-1$
$y=-2x+5$
The equation is now in slope-intercept form and according to that form, which is $y=mx+b$, $b$ is the $y$-intercept of the line.
In this case, it can be seen that $b=5$, so the $y$-intercept of the line is $(0,5)$
