The first thing to do in this case is to replace the value of x = 60 in the given function to obtain the average fuel mileage in miles per gallon. We then have to replace: y = -0.0088 * x ^ 2 + 0.79 * x + 15 y = -0.0088 * (60) ^ 2 + 0.79 * (60) + 15 y = 30.7 mi / gal answer the best approximate for the average gas mileage at a speed of 60 miles per hour is B) 30.7 mi / gal
