Find the Inverse of the Function $f ( x ) = 3 x + 2$

Multiple Choice

Find the inverse of the function. $f ( x ) = 3 x + 2$

A) $f ^ { - 1 } ( x ) = x - 2$
B) $f ^ { - 1 } ( x ) = 2 x$
C) $f ^ { - 1 } ( x ) = \frac { x + 2 } { 3 }$
D) $f ^ { - 1 } ( x ) = \frac { x - 2 } { 3 }$
E) none of these