Answer
$f\left( \dfrac{1}{3} \right)=3$
Work Step by Step
Substituting $x$ with $
\dfrac{1}{3}
$ in the given function, $
f(x)=-3x+4
,$ then,
\begin{array}{l}\require{cancel}
f\left( \dfrac{1}{3} \right)=-3\left( \dfrac{1}{3} \right)+4
\\\\
f\left( \dfrac{1}{3} \right)=-1+4
\\\\
f\left( \dfrac{1}{3} \right)=3
.\end{array}