A monopoly with constant marginal costs of $50 can sell to three groups of potential consumers, with demands q1 = 800 - 0.2p, q2 = 400 - p, and q3 = 700 - 0.4p respectively. find the optimal price- quantity combination in each market (i) if the firm is able to price-discriminate; (ii) if it is not able to price-discriminate.