Answer:
[tex]\boxed{\sf \ \ f^{-1}(x)=\dfrac{x-6}{3} \ \ }[/tex]
Step-by-step explanation:
hello,
we can write
[tex]fof^{-1}(x)=x \ and \ fof^{-1}(x)=f(f^{-1}(x))=3f^{-1}(x)+6 \ so\\3f^{-1}(x)+6=x \ \ subtract \ 6\\<=>3f^{-1}(x)=x-6 \ \ divide \ \ by \ \ 3\\<=> f^{-1}(x)=\dfrac{x-6}{3}[/tex]
hope this helps
