Two friends, Grayson and Santiago, had just bought their first cars. The equation \( y=31.9 x \) represents the number of miles, \( y \), that Santiago can drive his car for every \( x \) gallons of gas. Grayson uses 8 gallons of gas to drive 328.8 miles in his car. How many miles less does Santiago's car travel on one gallon of gas than Grayson's car?

To find out how many miles Santiago's car travels on one gallon of gas, we need to take the equation \( y = 31.9x \) and use \( x = 1 \) gallon. So, for Santiago’s car: \[ y = 31.9 \times 1 = 31.9 \text{ miles} \] Next, we need to determine how many miles Grayson’s car travels per gallon. Grayson drives 328.8 miles with 8 gallons of gas, so we find the miles per gallon (MPG) for Grayson: \[ \text{MPG} = \frac{328.8 \text{ miles}}{8 \text{ gallons}} = 41.1 \text{ miles per gallon} \] Now, we will find the difference in miles per gallon between Grayson’s and Santiago’s cars: \[ \text{Difference} = 41.1 - 31.9 = 9.2 \text{ miles} \] Therefore, Santiago's car travels 9.2 miles less on one gallon of gas than Grayson’s car.