A firm has 300000 shares of preferred stock outstanding which is selling for $70 a share. it also has 500000 shares of common stock outstanding, which is selling for $50 a share. the firm has no debt. the preferred dividend is $8.50 a share. The common dividend just paid was $2.50 a share. Common dividends are expected to grow at a 9% annual rate. What is this firms cost of capital?