Please explain how to do it in excel

The effect of tax rate on 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, 20% preferred stock, and 45% common stock. The cost of financing with retained earnings is 15%, the cost of preferred stock financing is 9%, and the before-tax cost of debt financing is 9%. Calculate the weighted average cost of capital (WACC) given a tax rate of 25%. The firm's WACC is %. (Round to two decimal places.)