Thelma and Louise are neighbors. During the winter, it is impossible for a snowplow to clear the street in front of Thelma's house without clearing the front of Louise's house. Thelma's marginal benefit (measured in $-dollars) from snowplowing services is MB(Thelma) = 12-Z where Z is the number of times the street is plowed. Louise's marginal benefit is MB(Louise) = 8-2Z. The marginal costs of getting the street plowed is constant at $16 (i.e. meaning that MC = $16). Use a graph and sketch the two private marginal benefit curves and the total marginal benefit curve. Draw in the marginal cost curve, and find the efficient level of provision for snowplowing services..