Solve the Problem $\mathrm { f } ( \mathrm { x } )$

Multiple Choice

Solve the problem.
-Bob buys a car that gets 13 miles per gallon of gasoline. Create a function, $\mathrm { f } ( \mathrm { x } )$ , that represents the number of miles that Bob can travel with $x$ gallons of gasoline.

A) $f ( x ) = 13 x$
B) $f ( x ) = x + 13$
C) $f ( x ) = \frac { 13 } { x }$
D) $f ( x ) = \frac { x } { 13 }$