A study conducted by a department of transportation regarding driving speed and mileage for midsize automobiles resulted in the data: X (speed in mph) 30 50 40 55 30 25 60 25 50 55 Y (mileage in mpg) 28 25 25 23 30 32 21 35 26 25 x = 420; y = 270; x2 = 19,300; y2 = 7,454; xy = 10,865 Find the equation of the least squares line