Ninecent Corporation has a target capital structure of $60$ percent common stock, $5$ percent preferred stock, and $35$ percent debt. Its cost of equity is $9$ percent, the cost of preferred stock is $7$ percent, and the pretax cost of debt is $8$ percent. The relevant tax rate is $21$ percent.

a$.$ What is the company's WACC? $($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? $($Do not round intermediate calculations and enter your answer as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$