your friends demand function for a soup at a restaurant is Qd = 4-0.2P(soup) +0.3P(steak)

Current price of soup (P soup) is $5 and the price of steak is (P steak) $20

a. Calculate the own-price elasticity of the demand for soup

b. Is the demand for soup elastic or inelastic at the given price? Please explain

c. Given the above demand function, are steak and soup substitutes or complements? Explain

d. If the restaurant wanted to increase its revenues from your friend, should they increase or decrease the price of soup? Why? What is the price of soup that maximizes the restaurant's revenues, assuming that all consumers have the same demand function?