Ninecent Corporation has a target capital structure of $70$ percent common stock, $5$ percent preferred stock, and $25$ percent debt. Its cost of equity is $11$ percent, the cost of preferred stock is $5$ percent, and the pretax cost of debt is $6$ percent. The relevant tax rate is $23$ percent.

a$.$ What is the company's WACC?

Note: Do not round intermediate calculations and enter your answer as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.$

b$.$ What is the aftertax cost of debt?

Note: Do not round intermediate calculations and enter your answer as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.$