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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. $900 per year for 16 years at 12%. b. $450 per year for 8 years at 6%. $ c. $400 per year for 8 years at 0%. $ d. Rework previous parts assuming they are annuities due. Present value of $900 per year for 16 years at 12% : $ Present value of $450 per year for 8 years at 6% : $ Present value of $400 per year for 8 years at 0%:$