产业经济学的问题，有没有会的大神们帮忙给看看啊。谢谢啦。
1. A publisher is facing the following situation:

                            High Type        Low Type
Hard cover             100                  50
Paper back              40                   30
No. of customer         40                 60
The production costs are zero.

(a) What is the optimal price if the firm can distinguish who is high/low?
(b) What is the price and profit if the publisher decides to sell only the Hardcover version?
(c) Please get the firm’s optimal prices for hard-cover and paper-back when it decides to sell both versions (hard-cover to high type; paper-back to low type)?

2. There are two types of potential consumers of equal number – 1 business and 1 academic customer. Each business customer has the demand function, Q=10-P, and each academic customer has the demand, Q=8-P. The marginal cost of providing service is two. The firm charges a two-part tariff, a fixed payment and t per quantity sold.

(a) Suppose that the seller can tell business from academic customers. What is the firm’s optimal fixed fee and variable fee for each group? What are the firm’s profits?
(b) Suppose that the seller were unable to keep the two types of customers separate. If the firm charges zero fixed fee, then what variable fee maximizes the firm’s profits?
(c) Suppose that the firm sets up one two-part tariff, what is the firm’s optimal two-part tariff?

3. Firms A and B both use a neighborhood copy center do make all their photocopies.  Firm A makes 200-3p copies a month and Firm B makes 60-p, when the copy center charges p per copy. The copy center optimally charges 40￠ per copy.  

Suppose that the copy center is closed out and that a manufacturer of copiers leases both firms a copier. Since the manufacture knows each firm’s demand curve, it would charge a two-part tariff (monthly fixed fee and variable fee) for each firm. Please get the manufacturer’s optimal two part tariff for each firm A and B.
[Hint: This question does not provide information about how much it cost per copy. You must get it from the question. Then, solve the optimal two part tariff structure.