For the Given Functions F and G , Find the Indicated

Multiple Choice

For the given functions f and g , find the indicated composition.
- $$f ( x ) = \frac { x - 9 } { 7 } , \quad g ( x ) = 7 x + 9$$
$( g \circ f ) ( x )$

A) $x$
B) $7 x + 54$
C) $x + 18$
D) $x - \frac { 9 } { 7 }$