turnbull company has a target capital structure of 58% debt, 6% preferred stock, and 36% common equity. it has a before-tax cost of debt of 8.20%, and its cost of preferred stock is 9.30%. if turnbull can raise all of its equity capital from retained earnings, its cost of common equity will be 12.40%. however, if it is necessary to raise new common equity, it will carry a cost of 14.20%.