Prices and quantities demanded for Overpriced Economics Textbooks are as follows: P Q $50 1,350 $55 1,100 (a) Calculate the approximate elasticity of demand when price is $55 using the percentage method (starting from $55 as the base year). (b) If the publisher raised the price to $60, what would be the approximate change in revenue (please be sure to note if it is an increase or a decrease)