Can someone help me with the formulas to use for 5 and 6

Robert Blanding's employer offers its workers a two-month paid sabbatical every seven years. Robert, who just started working for the firm, plans to spend his sabbatical touring Europe at an estimated cost of $25, 000. To finance his trip, Robert plans to make six annual end-of-year deposits of $2, 500 each, starting this year, into an investment account earning 8 percent interest. a. Will Robert's account balance at the end of seven years be enough to pay for his trip? b. Suppose Robert increases his annual contribution to $3, 150. How large will his account balance at the end of seven years? Robert Williams is considering an offer to sell his medical practice, allowing him to retire five years early. He has been offered $500, 000 for his practice and can invest this amount in an account earning 10 percent per year, compounded annually. If the practice is expected to generate the following cash flows, should Robert accept this offer and retire now? Gina Coulson has just contracted to sell a small parcel of land that she inherited a few years ago. The buyer is willing to pay $24, 000 at the closing of the transaction or will pay the amounts, shown in the following table