Demand for a product is given by$,$ P$($Qd$)=21500$ Qd$.$ The product is supplied by two firms that produce identical products, each of which has MC $=1$ and no fixed costs. Each firm maximizes profit assuming that the other$$s output will not change $($Cournot behavior$).($a$)$ Derive each firm$$s best$-$response function $($best$-$response function$).($b$)$ Calculate the Cournot$-$Nash equilibrium price, quantity, and profit of each firm. $($c$)$ If the two firms operated as one and maximized joint profits $($$1+$ $2),$ what would be the price, quantities, and profits?