The following shows the demands and marginal revenue in two markets, 1 and 2, for a price discriminating firm along with total marginal revenue,MR_T, and marginal cost MC

\fThe graph shows two sets of demand (DI. g] and marginal revenue [MRI . MR3] curves. with quantity on the horizontal axis. and price and cost in dollars on the vertical axis. D1 and MR1 have vertical intercepts of $50G: MR1 has horizontal intercept of t] units. and DI would have horizontal intercept of 1212] units {not shown}. B; and MR3 have vertical intercepts of $Ii-t]; MR3 has horizontal intercept of 4t] units. and D; has horizontal intercept of Bi] units. A total marginal revenue curve {MET} is shown. beginning at {20 units. $40G. where it coincides with MR1} and sloping down to end at {at} units. $1 IUD}. Marginal cost M C is shown decreasing below 12 units of output. and increasing after 12 units of output {minimum MC is at [12 units. $193)}: MC intersects MR3 at about 1:21 units. $195): D: at about [32 units. $2M); MRI at about {34 units. 5255]; MR1- at about [ti-t] units. $30G); and D1 at about [4? units. 53m}