The coupon rate on an issue of debt is $9\%.$ The yield to maturity on this issue is $13\%.$ The corporate tax rate is $31\%.$ What would be the approximate after$-$tax cost of debt for a new issue of bonds?

Note: Round your answer to $2$ decimal places.

Multiple Choice

$10\mathrm{.}42\%$

$8\mathrm{.}97\%$

$7\mathrm{.}62\%$

$11\mathrm{.}12\%$