FIN Corp. has determined that its before-tax cost of debt is 9.0%. Its cost of preferred stock is 12.0%. Its cost of internal equity is 15.0%, and its cost of external equity is 19.0%. Currently, the firm's capital structure has $400 million of debt, $100 million of preferred stock, and $500 million of common equity. The firm's marginal tax rate is 40%. The managers have determined that the firm should have $80 million available from retained earnings for investment purposes next period. What is the firm's marginal cost of capital (WACC) at a total investment level of $200 million