Chapter 2 - Functions - 2.5 Preview of Composite and Inverse Functions - Exercises and Problems for Section 2.5 - Exercises and Problems - Page 103: 34

$g^{-1}(C)=\frac{1}{45}(C-600)$

We solve the equation $C=g(x)=600+45 x$ for $x$. Subtract 600 from both sides and divide both sides by 45 to get $\begin{gathered}x=\frac{1}{45}(C-600) \\ g^{-1}(C)=\frac{1}{45}(C-600)\end{gathered}$