If the Function Is One-To-One, Find Its Inverse $$f ( x ) = \frac { 4 } { x + 7 }$$

Multiple Choice

If the function is one-to-one, find its inverse. If not, write "not one-to-one."
- $$f ( x ) = \frac { 4 } { x + 7 }$$

A) $f ^ { - 1 } ( x ) = \frac { - 7 x + 4 } { x }$
B) $f ^ { - 1 } ( x ) = \frac { x } { 7 + 4 x }$
C) not a one-to-one
D) $\mathrm { f } ^ { - 1 } ( \mathrm { x } ) = \frac { 7 + 4 \mathrm { x } } { \mathrm { x } }$