Assume that Firm U (the upstream firm) sells steel to firm D (the downstream firm). Firm D then uses the steel to make widgets. Both firms are monopolies. The demand for widgets is given by the equation P=100−Q. Furthermore, it takes 1 pound of steel to make one widget, which implies that Q also corresponds to the pounds of steel. The marginal revenue of firm D is MR=100−2Q, and the conversion cost for widgets is C=$10. (a) Derive Firm D's demand for steel. (b) What is firm U's marginal revenue line? (Hint: when demand is linear, the marginal revenue line has the same y-intercept as the demand line with twice the slope.) (c) Assuming that Firm U produces steel at a marginal cost of MC U=$10, what is Firm U's profit maximizing price and quantity for steel? (d) What is the price and quantity of widgets?