A vehicle is running at a constant speed of 60 mph on a highway. When it started it had 10 gallons of gasoline in its cylinder. The vehicle travels 30 miles on each gallon of gasoline ignore the initial acceleration at the start and final deceleration when the vehicle runs out of gasoline, and comes to a halt. Model the amount of gasoline in the vehicle as a linear function of time and graph it in the coordinate grid after how many hours will the vehicle run out of gas?