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 Tc = 0.40. a. A $1,600, one-year loan at 8%. (Do not round intermediate calculations. Round your answer to 2 decimal places.) b. A six-year loan of $1,600 at 8%. Assume no principal is repaid until maturity. (Do not round intermediate calculations. Round your answer to 2 decimal places.) c. A $1,600 perpetuity at 7%