You need to get gasoline for your car. You can drive ten miles to a gas station on the outskirts of town and save 10 cents per gallon on the price of gasoline.
If gasoline costs $3 per gallon and your car gets 25 miles per gallon for in-town driving, how many gallons of gasoline must you buy at the edge-of-town station to save enough on your fill up to pay for the cost to going to the station and back?
Ignore the wear-and-tear cost of operating your car in this example. (Enter your answer as a number without the units of gallons.)