Suppose the demand curve for a product is given by Q  10  2P  PS, where P is the price of the product and PS is the price of a substitute good. The price of the substitute good is $2.00.
a. Suppose P  $1.00. What is the price elasticity of demand? What is the cross-price elasticity of demand?
b. Suppose the price of the good, P, goes to $2.00. Now what is the price elasticity of demand? What is the cross-price elasticity of demand?