Assume the price of gasoline in 2004 was on the average $1.35 a gallon and 15 million gallons a day were sold. In 2005 , the price on the average was $2.15 a gallon and 14 million gallons were sold. Assuming further that the demand for gasoline did not shift between the two years, use the midpoint formula to calculate the price elasticity of demand and indicate whether demand was elastic or inelastic..