Chapter 6 - Section 6.6 - Rational Equations and Problem Solving - Exercise Set - Page 387: 4

$S=\dfrac{C}{1-P}$

Using the properties of equality, in terms of $ S ,$ the given equation, $ P=1-\dfrac{C}{S} ,$ is equivalent to \begin{array}{l} \dfrac{C}{S}=1-P \\\\ C=S(1-P) \\\\ \dfrac{C}{1-P}=S \\\\ S=\dfrac{C}{1-P} .\end{array}