The A-1 Corporation supplies airplane manufactures with preformed aircraft skin panels that are used on the exterior of aircraft. Aircraft skin forming machines required to manufacture these panels can be leased on an as needed basis for $12,500 each. Given the complexity of working with exotic metals used in the manufacturing process, workers are highly skilled and must be retained at all times. The market price for one of A-1's panels is $70. Based on the production data in the following table, how many aircraft skin forming machines should A-1 lease to maximize profits?