Penny's Budget Gourmet Restaurants has a current capital structure that is 70% equity, 20% debt, and 10% preferred stock. This is considered optimal. Penny is considering a $100 million capital budgeting project. Penny has estimated the following: After-tax cost of debt: 7.0% Cost of preferred stock: 8.0% Cost of internal equity: 13.0 % Cost of external equity: 15.0% Penny expects to have $40 million of new retained earnings available to finance this project. What is Marion's cost of capital for this project?