The WACC K. Bell Jewelers wishes to explore the effect on its cost of capital of the rate at which the company pays taxes. The firm wishes to maintain a capital structure of 35% debt, 10% preferred stock, and 55% common stock. The cost of financing with retained earnings is 15%, the cost of preferred stock financing is 12%, and the before-tax cost of debt financing is 8%. Calculate the weighted average cost of capital (WACC) given a tax rate of 21%.