Calculate: 7+5

Expression: $-3x-y=12$

Rewrite the equation in slope-intercept form

$y=-3x-12$

Subtracting is the same as adding the opposite

$y=-3x+\left( -12 \right)$

Since the equation is written in slope-intercept form, $y=mx+b$, identify the slope of the line as the coefficient next to the variable $x$

$\begin{array} { l }y=-3x+\left( -12 \right),& m=-3\end{array}$

Identify the $y$-intercept of the line as the constant term

$\begin{array} { l }y=-3x+\left( -12 \right),& m=-3,& b=-12\end{array}$

The slope of the line is $m=-3$ and the $y$-intercept is $b=-12$

$\begin{array} { l }m=-3,& b=-12\end{array}$