Using regression analysis on data from a field experiment, the demand curve for a product is estimated to be $,$ where Pz $=$ $$300.($LO$1,$ LO$4,$ LO$5)$

What is the own price elasticity of demand when Px $=$ $$140?$ Is demand elastic or inelastic at this price? What would happen to the firm$$s revenue if it decided to charge a price below $$140?$

What is the own price elasticity of demand when Px $=$ $$240?$ Is demand elastic or inelastic at this price? What would happen to the firm$$s revenue if it decided to charge a price above $$240?$

What is the cross$-$price elasticity of demand between good X and good Z when Px $=$ $$140?$ Are goods X and Z substitutes or complements?