Q1. Chap 5 (Part I: Nash Equilibrium of Bertrand Model): Consider a Bertrand model (price competition model). The market demand equation is P=140-Q. Consumers only buy from the firm whose price is lower. If both firms charge the same price, they share the market equally. The marginal cost for firm 1 is 20, and the marginal cost for firm 2 is also 20. There are no fixed costs. (Q1A) Find the Nash equilibrium and briefly explain your reason. (Q1B) Suppose now firm 2's marginal cost rises to 30 and all the other conditions remain the same. Find the new Nash equilibrium and briefly explain your reason