## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$n=\dfrac{9(M-18)}{5}$
Using the properties of equality, in terms of $n$, the given equation, $M=\dfrac{5}{9}n+18$, is equivalent to \begin{array}{l} M-18=\dfrac{5}{9}n \\\\ \left(\dfrac{9}{5} \right)(M-18)=\left( \dfrac{5}{9}n \right)\left(\dfrac{9}{5} \right) \\\\ \\\\ n=\dfrac{9(M-18)}{5} .\end{array}