Great Seneca Inc. sells $100 million worth of 23 -year to maturity 6.69% annual coupon bonds. The net proceeds (proceeds after flotation costs) are $980 for each $1,000 bond. The firm?s marginal tax rate is 40%. What is the after-tax cost of capital for this debt financing? Round the answer to two decimal places in percentage form. (Write the percentage sign in the units box)