Problem:
Karl's car uses a gallon of gas every miles, and his gas tank holds gallons when it is full. One day Karl started with a full tank of gas, drove miles, bought 8 gallons of gas, and continued driving to his destination. When he arrived, his gas tank was half full. How many miles did Karl drive that day?
Answer Choices:
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Solution:
In driving miles, Karl used gallons of gas, so he had gallons left in his tank. After buying more gallons, he had gallons. When he arrived at his destination, he had gallons left, so he used an additional gallons. This let him drive an additional miles, so he drove a total of miles.
Karl used gallons of gas on his trip, so he drove miles.
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions