Solve the Problem $f ( x ) = m x + b$

Multiple Choice

Solve the problem.
-Given $f ( x ) = m x + b$ , find $m$ and $b$ if $f ( - 6 ) = - 7$ and $f ( - 12 ) = - 11$ .

A) $m = \frac { 3 } { 2 } ; b = - 3$
B) $m = \frac { 3 } { 2 } ; b = 3$
C) $m = \frac { 2 } { 3 } ; b = 3$
D) $m = \frac { 2 } { 3 } ; b = - 3$