Your friend Bob, is going through some tough time financially and you want to help him out. You are negotiating to lend a 7-year loan of $30,000 to him. To repay you, Bob will pay $4,000 at the end of Year 1, $6,000 at the end of Year 2, and $8,000 at the end of Year 3, plus a fixed but currently unspecified cash flow, X, at the beginning of Years 4 through 7. Because you and Bob are long-time friend, you are confident that Bob will make all 7 yearly payments. You regard 9% as an appropriate rate of return on this 7-year loans. What amount does Bob have to pay from Year 4 to Year 7 (i.e., what is X?). To clarify, the amount X is same from Year 4 to Year 7.