Respuesta :

Think of f(x) as y(x) and inverse function as x(y).
[tex]f^{-1} (3) = x(3)[/tex]
So y = 3, solve for x

[tex]f(x) = y = \frac{x+5}{3} \\ \\ \frac{x+5}{3} = 3 \\ \\ x+5 = 9 \\ \\ x = 4[/tex]

Therefore,
[tex]f^{-1} (3) = 4[/tex]