Which formula is correct for calculating gas mileage?

The correct formula for calculating gas mileage is based on dividing the number of miles driven by the gallons of gas consumed. This gives you a measurement of how many miles each gallon of fuel allows the vehicle to travel, which is commonly expressed in miles per gallon (MPG). This calculation directly reflects the fuel efficiency of the vehicle, providing a clear understanding of how far you can go with a certain amount of fuel.

Other options do not accurately represent how gas mileage is typically calculated. For instance, dividing total miles driven by the capacity of the gas tank does not indicate the actual fuel consumption during a trip. Similarly, calculating gallons of gas divided by total miles driven would yield a figure that reflects fuel usage in a different context, which is not how we conventionally assess gas mileage efficiency.