Find the Inverse of the One-To-One Function $$y = 3 x + 9$$

Multiple Choice

Find the inverse of the one-to-one function. $$y = 3 x + 9$$

A) $\quad y = \frac { x + 9 } { 3 }$
B) $\quad y = \frac { x - 3 } { 9 }$
C) $\quad y = \frac { 3 } { x - 9 }$
D) $\quad y = \frac { x - 9 } { 3 }$
E) none of the above