Klose Outfitters Inc. believes that its optimal capital structure consists of 60% common equity and 40% debt, and its tax rate is 40%. Klose must raise additional capital to fund its upcoming expansion. The firm will have $2 million of new retained earnings with a cost of rs = 12%. New common stock in an amount up to $6 million would have a cost of re = 15%. Furthermore, Klose can raise up to $3 million of debt at an interest rate of rd = 10%, and an additional $4 million of debt at rd = 12%. The CFO estimates that a proposed expansion would require an investment of $5.9 million. What is the WACC for the last dollar raised to complete the expansion?