A civil engineering consulting firm is evaluating its cash flow requirements for the next 7 years. The company expects to replace computer equipment and furniture at various times over the 7-year planning period. Specifically, the company expects to spend $6,000 two years from now, 9,000 three years from now, and 5,000 six years from now. If the CEO wants to invest a sum today for the improvements in the next 7 years, how much should be invested at a rate of 10%?