Suppose that Abigail and Betsy are the only two producers in a market, and Abigail is producing 30 units and Betsy is producing 40 units. When Abigail is producing 30 units, Betsy maximizes her profit by producing 50 units, and when Betsy produces 40 units, Abigail maximizes her profit by producing 40 units. When Abigail produces 30 units and Betsy produces 40 units.