James Smith recently fulfilled his long$-$time dream of opening a gym that offers spinning exercise classes for $$10$ per person. To differentiate his gym and better serve his clients, James provides a towel, a bottle of water, and an after$-$workout protein shake to each person participating in a class, at a cost of $$1\mathrm{.}75$ per person. James employs four part$-$time instructors and pays them each $$1,000$ per month. He also pays himself a monthly salary of $$5,500.$ James$$s other monthly costs are $$1,500$ for rent, $$1,250$ for depreciation on his $30$ bikes, and $$1,400$ in utilities and insurance.