5 years ago, Barton Industries issued 25-year noncallable, semiannual bonds with a $2,100 face value and a 9% coupon, semiannual payment ($94.5 payment every 6 months). The bonds currently sell for $845.87. If the firm's marginal tax rate is 40%, what is the firm's after-tax cost of debt? Do not round intermediate calculations. Round your answer to two decimal places. %