I already submitted this question once and I was given 6.71 and 6.87 as answers for c (depending on whether it was calculated by book weight or market weight) but the check my work feature says that both those answers are incorrect. Please show your work and/or excel formulas used so I know how to do this myself.

Marysa Corp. issued a 20-year, 9 percent semiannual bond 3 years ago. The bond currently sells for 96 percent of its face value. The book value of the debt issue is $40 million. In addition, the company has a second debt issue on the market, a zero coupon bond with 10 years left to maturity; the book value of this issue is $40 million and the bonds sell for 55 percent of par. The company's tax rate is 23 percent. a. What is the company's total book value of debt? (Do not round intermediate calculations and enter your answer in dollars, not millions of dollars, e.g., 1,234,567.) b. What is the company's total market value of debt? (Do not round intermediate calculations and enter your answer in dollars, not millions of dollars, e.g., 1,234,567.) c. What is your best estimate of the aftertax cost of debt? (Do not round intermediate calculations and enter your answer as a percent rounded to 2 decimal places, e.g., 32.16.) Answer is complete but not entirely correct