When going more than 38 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 and y is the miles per gallon of gasoline. Based on this model, at what speed will the car average 15 miles per gallon? (Round to nearest whole number.)
Accepted Solution
A:
15= 43.81-.395x move the 43.81 to the other side by subtracting it on both sides. -28.81=-.395x divide -28.81 by -.395 and get x x=72.9367= 73 miles per hour to get 15 miles per gallon