need help on following on how to solve. The answers are in bold but need help figuring out how to get to these answers.

-Suppose you inherited $100,000 and invested at 7% per year. What is the most you could withdraw at the end of each of the next 10 years and have a zero balance at year 10? How would your answer change if you made withdrawls at the beginning of each year? ($14,237.75, $13,306.31)

-If you had $100,000 that was invested at 7% and you wanted to withdraw $10,000 at the end of each year, how long would your funds last? How long would they last if you earned 0%? How long would they last if you earned the 7% but limited your withdraws to $7,000 per year? (17.8 years, 10years;forever)

-Your uncle named you beneficiary of his life insurance policy. The insurance company gives you a choice of $100,000 today or a 12-year annuity of $12,000 at the end of each year. What rate of return is the insurance company offering? (6.11%)

-assume that you just inheritted an annuity payment that will pay you $10,000 per year for 10 years, with the first payment being made today. A friend of your mother offers to give you $60,000 for the annuity, if you sell it, what rate of return would your mothers friend earn on his investment? if you think a "fair" return would be 6%, how much should you ask for the annuity? (13.70%, $78,016.92)