Answer
$\$102.6$
Work Step by Step
We have the proportion
$$
\frac{28.5}{5}=\frac{x}{18}
.$$
By setting the product of the means and the product of the extremes equal, we have
$$
5\cdot x=28.5\cdot 18\Longrightarrow x=\frac{28.5\cdot 18}{5}=102.6
.$$
