Please help me with #3. Please show the formula and how to use it

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2. 3. Suppose that you borrow $8,000 now, promising to repay the loan principal plus accumulated interest rate in four years at r=10% per year. How much would you repay at the end of four years? Alex has an option to purchase a tract of land that will be worth $10,000 in six years. If the value of the land increases at 8% each year. How much should Alex be willing to pay now for this property? An enterprising student is planning to have personal savings totaling $1,000,000 when she retires at age 65. She is now 20. If the annual interest rate will average 7% over the next 45 years on her saving account, what equal end-of year amount must she save to accomplish her goal? Suppose that a father, on the day his son is born, wishes to determine what lump amount would have to be paid into an account bearing interest 12% per year to provide withdrawals of $2,000 on each of the son's 18th, 19th, 20th, and 21st birthdays