Marginal Incorporated (MI) has determined that its before-tax cost of debt is 10.0%. Its cost of preferred stock is 11.0%. Its cost of internal equity is 14.0%, and its cost of external equity is 18.0%. Currently, the firm's capital structure has $470 million of debt, $150 million of preferred stock, and $380 million of common equity. The firm's marginal tax rate is 25%. The firm is currently making projections for the next period. Its managers have determined that the firm should have $92 million available from retained earnings for investment purposes next period. What is the firm's marginal cost of capital at a total investment level of $358 million?