A delivery company is analyzing its fuel costs for two types of vehicles: vans and trucks. The table below shows the average fuel efficiency and the average cost per gallon for each vehicle type.
| Vehicle Type | Fuel Efficiency (miles/gallon) | Cost per gallon ($) |
|---|---|---|
| Van | 25 | 3.20 |
| Truck | 15 | 3.50 |
The equation gives the total fuel cost, , in dollars, for a month, where is the total miles driven by vans and is the total miles driven by trucks. The company also uses motorcycles for smaller deliveries, which are included in the total cost. Which of the following is the best interpretation of in this context?
The total number of gallons of fuel used by motorcycles
The cost of all the fuel used by motorcycles
The average cost per gallon of fuel for motorcycles
The total miles driven by motorcycles
