Deltatronics, Inc., is considering investing in one of two audio equipment, Som and Tingull, that are both equally effective in their functionality. However, they differ in their purchase costs, the number of years they last, and the operating cost each year. Som

and has annual operating costs of $$500$ each year. Tingull

years, and has annual operating costs of $$700$ each year. Assume Deltatronics has an annual discount rate of $10\%.$ Which of the two audio equipment should it buy? Show all your work.