Helms Aircraft has a capital structure that consists of 60 percent debt and 40 percent common stock. The firm will be able to use retained earnings to fund the equity portion of its capital budget. The company recently issued bonds with a yield to maturity of 9 percent. The risk-free rate is 6 percent, the market risk premium is 6 percent, and Helms' beta is equal to 1.5. If the company's tax rate is 35 percent, what is the company's weighted average cost of capital (WACC)