​Laurel, Inc., has debt outstanding with a coupon rate of 5.9 % and a yield to maturity of 7.1 %. Its tax rate is 40 %. What is​ Laurel's effective​ (after-tax) cost of​ debt? ​ NOTE: Assume that the debt has annual coupons. ​Note: Assume that the firm will always be able to utilize its full interest tax shield.