Compute the present value of interest tax shields generated by these three debt issues. Consider corporate taxes only. Assume that the marginal tax rate is -0.34. a. A $1,900, one-year loan at 7%. Note: Do not round intermediate calculations. Round your answer to 2 decimal places. b. A three-year loan of $1,900 at 7%. Assume no principal is repaid until maturity. Note: Do not round intermediate calculations. Round your answer to 2 decimal places. c. A $1,900 perpetuity at 6%. a. Present value b. Present value c. Present value