World Laundry Supplies capital structure is as follows:

Debt............................ 40%

Preferred stock ........... 15%

Common equity.......... 45%

The after-tax cost of debt is 7.0 percent; the cost of preferred stock is 10 percent; and the cost of common equity (in the form of retained earnings) is 13.5 percent. Calculate World Laundry Supplies weighted average cost of capital.