Tawanna is considering starting a small business. She plans to purchase equipment costing $145,000. Rent on the building used by the business will be $24,000 per year while other operating costs will total $30,000 per year. A market research specialist estimates that Tawanna's annual sales from the business will amount to $90,000. Tawanna plans to operate the business for 6 years. Disregarding the effects of taxes, what will be the amount of annual net cash flow generated by the business?

a. $36,000
b. $54,000
c. $90,000
d. None of the above