ach of Northview's production managers $($annual salary cost, $$45,000)$ can oversee $60,000$ machine hours of manufacturing activity. Thus, if the

ompany has $50,000$ hours of manufacturing activity, one manager is needed; for $75,000$ hours, two managers are needed; for $125,000$ hours, three

nanagers are needed; and so forth. Northview's salary cost can best be described as a: