help please

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 12 percent, the cost of preferred stock is 6 percent, and the pretax cost of debt is 7 percent. The relevant tax rate is 24 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., 32.16.) 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., 32.16.)