5-6. (Present value of an annuity) what is the present value of the following annuities? A. $2,500 a year for 10 years discounted back to the present at 7 percent B. $70 a year for 3 years discounted back to the present at 3 percent C. $280 a year for 7 years discounted back to the present at 6 percent D. $500 a year for 10 year for 3 years compounded annually at 2 percent