Question: When going more than thirty-eight miles per hour, the gas mileage of a certain car fits the model y = 43.81 - .395x where x is the speed of the car in miles per hour & y is the miles per gallon of gasoline. Based on this model, at what speed will the car average fifteen miles per gallon? [Round to nearest whole number.]
[A] 149
[B] 98
[C] 73
[D] 48