Answer
$\text{slope: }
-\dfrac{3}{4}
,\\\\\text{$y$-intercept: }
3$
Work Step by Step
Using the properties of equality, the given equation, $
3x+4y=12
$, is equivalent to
\begin{array}{l}
4y=-3x+12
\\\\
y=-\dfrac{3}{4}x+\dfrac{12}{4}
\\\\
y=-\dfrac{3}{4}x+3
.\end{array}
Using $y=mx+b$ where $m$ is the slope and $b$ is the $y$-intercept, then the equation above has the following characteristics:
\begin{array}{l}
\text{slope: }
-\dfrac{3}{4}
,\\\\\text{$y$-intercept: }
3
.\end{array}