Please show step by step formulas.

27. Assuming an interest rate of 7%, compute how much income you will have each month if you save $150 each month for the next 40 years and then use the accumulated money to buy an annuity of equal monthly payments for 12 years (or an annuity for life when you expect to live for U more years). 28. Assuming an interest rate of 1.68%, compute how much income you will have each month if you save $150 each month for the next 40 years (and then retire) and then use the accumulated money to buy an annuity of equal monthly payments for 12 years (or an annuity for life when your life expectancy is U more years at that time). 29. Assuming an interest rate of 4.87%, compute how much income you will have each month if you save $150 each month for the next 40 years and then retire) and then use the accumulated money to buy an annuity of equal monthly payments for 12 years (or an annuity for life when your life expectancy is U more years at that time). 30. Assuming an interest rate of 4.87%, compute how much income you will have each month if you save $250 each month for the next 40 years and then retire) and then use the accumulated money to buy an annuity of equal monthly payments for 12 years (or an annuity for life when your life expectancy is U more years at that time)