What is the Future Value at year 8, of a $3,000 inflow at time zero (instantly), and a $1,000 outflow 6 years from now and a $4,000 inflow 7 years from now? Assume an interest rate of 10% for years 1, 2 and 3, 8% for years 4 and 5, and 15% for years 6, 7 and 8.