Find the present value of the following ordinary annuities: a. $400 per year for 10 years at 10% b. $200 per year for 5 years at 5% c. $ 400 per year for 5 years at 0% d. Now rework parts a, b, and c assume that payments are made at the beginning of each year, that is , they are annuities due. please give explanation on how to rework and why