Senior Company currently buys 35,000 units of a part used to manufacture its product at $40 per unit. Recently the supplier informed Senior Company that a 20 percent increase will take effect next year. Senior has some additional space and could produce the units for the following per-unit costs (based on 35,000 units): If the units are purchased from the supplier, $200,000 of fixed costs will continue to be incurred. in addition, the plant can be rented out for $20,000 per year if the parts are purchased externally. Should Senior Company buy the part externally or make it internally