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. $600 per year for 12 years at 8%. $ b. $300 per year for 6 years at 4%. $ c. $600 per year for 6 years at 0%. $ d. Rework previous parts assuming they are annuities due. Present value of $600 per year for 12 years at 8% : $ Present value of $300 per year for 6 years at 4% : $ Present value of $600 per year for 6 years at 0%:$