Rollins Corporation is constructing its marginal cost of capital (MCC) schedule. Its target capital structure is 30 percent debt, 20 percent preferred stock, and 50 percent common equity. Its bonds have a 12 percent coupon rate of interest, semiannual interest payments, a current maturity of 20 years, and a market value equal to their par value of $1,000. The firm's marginal tax rate is 40 percent. What is Rollins' after-tax cost of debt?