(Cost of debt) Belton Distribution Company is issuing a $1,000 par value bond that pays 8.4 percent annual interest and matures in 15 years that is paid semiannually. Investors are willing to pay $956 for the bond. The company is in the 20 percent marginal tax bracket. What is the firm's after-tax cost of debt on the bond? The firm's after-tax cost of debt on the bond is %. (Round to two decimal places.)