Task: Question Answering
Input (English): Problem: a certain car can travel 20 minutes on a gallon of gasoline at 60 miles per hour. if the car had started with a full tank and had 8 gallons of gasoline left in its tank at the end, then what percent of the tank was used to travel 80 miles at 60 mph ?
Options: a. 16.67 %, b. 20 %, c. 25 %, d. 30 %, e. 40 %
Output (English): a