Answer:
[tex]y = - \frac{4x}{107} + 12[/tex]
Step-by-step explanation:
You start with 12 gallons, and for every mile that you drive, you will deplete [tex]\frac{1}{321}[/tex] of your total amount of gas, or [tex]\frac{12}{321} = \frac{4}{107}[/tex] gallons of gas for every mile you drive. Thus, for every x miles you drive, you'll deplete [tex]\frac{4x}{107}[/tex] miles. Subtract that from 12 to get your final answer.