What is the WACC for a firm with 50% debt and 50% equity that pays 12% on its debt, 20% on its equity, and has a 40% tax rate?

Calculate a firm's WACC given that the total value of the firm is $2,000,000, $600,000 of which is debt, the cost of debt and equity is 10% and 15%, respectively, and the firm pays no taxes.

A company's CFO wants to maintain a target debt-to-equity ratio of 1/4. If the WACC is 18.6%, and the pretax cost of debt is 9.4%, what is the cost of common equity assuming a tax rate of 34%?

If a firm has three times as much equity as debt in its capital structure, then the firm has: 

What is the WACC for a firm with 40% debt, 20% preferred stock, and 40% equity if the respective costs for these components are 6% after tax, 12% after tax, and 18% before tax? The firm's tax rate is 35%