Use the Alphabet Coding Method (A =1, B = 2 $f ( x ) = 3 x - 4$

Essay

Use the alphabet coding method (A =1, B = 2, C = 3, ... Z = 26) to
-The function defined by $f ( x ) = 3 x - 4$ was used to encode a message as:
$$\begin{array} { l l l l l l l l l l } 38 & 11 & 62 & 11 & 50 & - 1 & 17 & - 1 & 23 & 38\end{array}$$
Find the inverse function and determine the message.