Find the present values of these ordinary annuities. Discounting occurs once a year. Do not round intermediate calculations. Round your answers to the nearest cent. a. $500 per year for 16 years at 8%. b. $250 per year for 8 years at 4%. $ c. $900 per year for 8 years at 0%. $ d. Rework previous parts assuming they are annuities due. Present value of $500 per year for 16 years at 8%: $ Present value of $250 per year for 8 years at 4%: $ Present value of $900 per year for 8 years at 0%: $