pls solve

Assume that a company needs to finance its valuable investment project using debt, preferred stocks and common stocks, it has decided to use $120 million of debt, 30 million of preferred stocks and 50 million of common stocks. The coupon interest rate on bond = 8% with a corporate income tax rate of 40% while the required return on preferred stock was 10% and was estimated to be 12% for common stock. What the Retaj company's WACC if its currently at its optimal capital structure