Solve the Problem $C$ Is Size 36 in Country D $D$ Is $f ( x ) = x + 30$

Multiple Choice

Solve the problem.
-A size 6 dress in Country $C$ is size 36 in Country D. A function that converts dress sizes in Country C to those in Country $D$ is $f ( x ) = x + 30$ . Find a formula for the inverse of the function described.

A) $f ^ { - 1 } ( x ) = x + 30$
B) $f ^ { - 1 } ( x ) = x - 30$
C) $f ^ { - 1 } ( x ) = \frac { x } { - 30 }$
D) $\mathrm { f } ^ { - 1 } ( \mathrm { x } ) = \frac { \mathrm { x } } { 30 }$