vineyard wines corp issued a $15$ year bonds three years ago. the bonds have an annual $6\mathrm{.}75$ per cent coupon rate and pay coupons semi annually. currently these bands are selling at $97\mathrm{.}8$ per cent of face value resulting on a yield to maturity og $7\mathrm{.}024$ per cent. what is the after tax cost of debt if the tax rate is $20$ per cent?