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. $200 per year for 12 years at 10%. $ b. $100 per year for 6 years at 5%. $ c. $900 per year for 4 years at 0%. $ d. Rework previous parts assuming they are annuities due. Present value of $200 per year for 12 years at 10% : $ Present value of $100 per year for 6 years at 5%:$ Present value of $900 per year for 4 years at 0%:$