Answer
$f(x)=-\dfrac{2}{3}x+4$
Work Step by Step
Using $y=mx+b$ or Slope-Intercept Form, the equation of the line with slope $
-\dfrac{2}{3}
$ and $y-$intercept $(
0,4
)$ is
\begin{array}{l}
y=-\dfrac{2}{3}x+4
.\end{array}
In function notation, this is equivalent to
\begin{array}{l}
f(x)=-\dfrac{2}{3}x+4
.\end{array}