A Size 44 Dress in Country C Is $f ( x ) = \frac { x } { 2 } - 20$

Multiple Choice

A size 44 dress in Country C is size 2 in Country D. A function that converts dress sizes in Country C to those in Country D is : $f ( x ) = \frac { x } { 2 } - 20$ . Find a formula for the inverse of this function.

A) $f ^ { - 1 } ( x ) = x + 20$
B) $f ^ { - 1 } ( x ) = 2 x + 20$
C) $f ^ { - 1 } ( x ) = 2 ( x - 20 )$
D) $f ^ { - 1 } ( x ) = 2 ( x + 20 )$