Distance covered in trip = 640 miles
The cost per mile = $0.08
The cost of the total trip:
[tex]\begin{gathered} Total\text{ }cost=\text{ Distance covered in the trip }\times\text{ cost per trip} \\ \text{Total cost = 640 miles }\times\text{ }\frac{\text{ \$}0.08\text{ }}{\text{mile}} \\ \text{Total cost = 640 }\times\text{ 0.08} \end{gathered}[/tex][tex]\text{Total cost of gasoline for the trip = \$51.20}[/tex]