Given that f(3) = 5 and f(3x) = f(x) + 3 for all x, find f^{-1}(11).
Note that \(f(9) = f(3) + 3 = 8\).
\(f(27) = f(9) + 3 = 11\).
Then, \(f^{-1}(11) = f^{-1}(f(27)) = 27\).
