A monopolist knows that there are two types of consumers, "high demand" (H) and low demand (L) types. Inverse demand for each consumer of the two types is P = 150 q^L' and P = 200 q^H. 60% of consumers are of the L type. Marginal cost is zero.

a) find the optimal price

b) Suppose the firm sets a fee, plus a price per unit. Show on a diagram.