Consider a demand curve given by Q" - 60 - = P. At what quantity along the demand curve is sales revenue maximized? (round your answer to two decimal places if necessary)Consider a demand curve given by Q (I, P) = 51 - P where I is the consumer's income. Suppose the price, P, is equal to $25. If income increases from $10 to $20, what is the income elasticity of demand using the midpoint method? (round your answer to two decimal places if necessary)