Answer
$\text{slope: }
-3
\\\text{$y-$intercept: }
\dfrac{1}{2}
$
Work Step by Step
The given expression, $
f(x)=-3x+\dfrac{1}{2}
,$ is equivalent to
\begin{array}{l}
y=-3x+\dfrac{1}{2}
.\end{array}
Using $y=mx+b$ (or the Slope-Intercept Form), where $m$ is the slope and $b$ is the $y-$intercept, then the equation above has the following characteristics:
\begin{array}{l}
\text{slope: }
-3
\\\text{$y-$intercept: }
\dfrac{1}{2}
.\end{array}