A firm has a capital structure that uses 45 percent equity, 20 percent preferred shares, and 35 percent debt. The preferred shares have a current yield of 5.5 percent. The debt has a coupon rate of 10 percent and a current yield to maturity of 6.5 percent. The common shares have a yield of 8 percent. The tax rate is 25 percent. What is the firm's WACC?