Bills demand for hamburgers (a private good) is Q = 20 2P and Teds demand is

Question:

Bill’s demand for hamburgers (a private good) is Q = 20 – 2P and Ted’s demand is
Q = 10 – P.
a. Write down an equation for the social marginal benefit of the consumption of hamburgers.
b. Now suppose that hamburgers are a public good. Write down an equation for the social marginal benefit of hamburger consumption.