9. [Hart and Tirole (1990)]. Consider a monopolist upstream supplier U1 selling to two downstream producers D1 and D2 engaged in Cournot competi-tion. Downstream demand is described by: P = 100 - Q and marginal cost is zero at both the upstream and downstream level. A) What price will U1 set? What will the downstream price be? Calculate the profits of Us, Da and Dz. Hint: suppose the price set by U is r; what will be the outcome in the downstream market? B) Imagine a contract by which U1 sells 25 units as a package to each of D1 and D2 at a price of $1,250. Each firm can either accept the package or reject it. Show that if decisions are made simultaneously, and each firm has full information about the other's actions, the Nash Equilibrium is for each to accept this offer