Answer
$\$77$
Work Step by Step
Substituting $x$ with $
100
$ in $C(x)=\dfrac{35x+4200}{x}$, then,
\begin{array}{l}\require{cancel}
C(100)=\dfrac{35(100)+4200}{100}
\\\\
C(100)=\dfrac{7700}{100}
\\\\
C(100)=77
.\end{array}
Hence, the average cost is \$77.
