The Miller family is taking a road trip to visit some relatives. With a full gas tank, the car has a range of 456 miles. Mr. Miller wants to stop to fill up when the range reaches 57 miles remaining. If the car averages 28.5 miles per gallon, then the equation 456 - 28.5g represents how many gallons of gas they will use before they need to fill up. How many gallons of gas will they use before they need to fill up? 57