A monopoly producer of glassware operates two plants whose marginal cost schedules are 1 = 60 + 0.21 and 2 = 48 + 0.42. a. Derive a formula for the firm's aggregate marginal cost schedule. Make sure to determine the output ranges over which the summed function applies. b. Graph the aggregate marginal cost schedule over the range 0 60, with on the axis and on the axis. To receive full credit, make sure to label the intercept values, the two slopes, and the coordinates at which the slope changes.