1. replace f(x) with y
[tex]y=4x+7[/tex]2. Replace every x with a y and replace every y with an x
[tex]x=4y+7[/tex]3. Solve for y:
[tex]\begin{gathered} 4y=x-7 \\ y=\frac{x-7}{4} \end{gathered}[/tex]4. Replace y with f−1(x):
[tex]f^{-1}(x)=\frac{x-7}{4}[/tex]Evaluate the inverse for x = 15:
[tex]f^{-1}(15)=\frac{15-7}{4}=\frac{8}{4}=2[/tex]