Shaken Corp. issued a bond with a maturity of 10 years and a semiannual coupon rate of 10 percent 4 years ago. The bond currently sells for 94 percent of its face value. The book value of the debt issue is $55 million. In addition, the company has a second debt issue on the market, a zero coupon bond with 14 years left to maturity; the book value of this issue is $30 million and the bonds sell for 55 percent of par. The company's tax rate is 38 percent.

I calculate total book value 850000000

I calculate Total Market value of debt 68200000

Please assist me with the best estimate of the aftertax cost of debt? I incorrectly calculate 4.93%. Please help!