Answer
The slope of the line given is $m=\dfrac{3}{4}$ and its $y$-intercept is $(0,-3)$
Work Step by Step
$f(x)=\dfrac{3}{4}x-3$
Substitute $f(x)$ by $y$, for representative purposes:
$y=\dfrac{3}{4}x-3$
The equation of this line is now in slope-intercept form. This form is $y=mx+b$, where $m$ is the slope of the line and $b$ is its $y$-intercept.
In this case, $m=\dfrac{3}{4}$ and $b=-3$
The slope of the line given is $m=\dfrac{3}{4}$ and its $y$-intercept is $(0,-3)$
The graph is shown below: