Answer:
9
Step-by-step explanation:
we know by definition that
[tex]f^{-1}(f(x))=x\\\\f^{-1}(\frac{2x}{3})=x\\\\f^{-1}(x)=ax\\\\f^{-1}(\frac{2x}{3})=a(\frac{2x}{3})=x\\\\f^{-1}(x)=\frac{3x}{2}[/tex]
so now we evaluate
[tex]f^{-1}(6)=\frac{3*6}{2}\\\\=3*3\\\\f^{-1}(6)=9[/tex]
and if we want to do an extra step
[tex]f^{-1}(f(6))=6\\\\f^{-1}(\frac{2*6}{3})=f^{-1}(4)=\frac{3*4}{2}=6[/tex]
which works.
