(Compound annuity) What is the accumulated sum of each of the following streams of payments? a. $500 a year for 8 years compounded annually at 9 percent. b. $104 a year for 8 years compounded annually at 9 percent. c. $38 a year for 12 years compounded annually at 13 percent. d. $24 a year for 5 years compounded annually at 6 percent