The Following Relationship Between Price,average Total Cost,and the Number of Firms

The following relationship between price,average total cost,and the number of firms describes an industry in a single country. (A)Graph the relationship between average total cost and the number of firms,as well as the relationship between price and the number of firms.
(B)Find the long-run equilibrium price and number of firms.
(C)Suppose the country opens to trade with other countries.Which line will shift and in which direction? What will happen to the long-run equilibrium price and the number of firms in the industry?