Golden Fleet Inc. believes that its optimal capital structure consists of 60% common equity and 40% debt, and its tax rate is 25%. Golden Fleet must raise additional capital to fund its upcoming expansion. The firm will have $6 million of retained earnings with a cost of r_s =11%. New common stock in an amount up to $10 million would have a cost of r_e =13.75%. Furthermore, Golden Fleet can raise up to $5.2 million of debt at an interest rate of r_d =7.5% and an additional $5 million of debt at r_d =13%. The CFO estimates that a proposed expansion would require an investment of $15.5 million. What is the WACC for the last dollar raised to complete the expansion?