Find the Requested Function Value $( g \circ f ) ( - 1 )$

Multiple Choice

Find the requested function value.
-Find $( g \circ f ) ( - 1 )$ when $f ( x ) = \frac { x - 7 } { 8 }$ and $g ( x ) = 8 x + 1$

A) $- 7$
B) 7
C) $- 9$
D) $- \frac { 7 } { 4 }$