A firm has determined its optimal capital structure which is composed of the following sources and target market value proportions. Please show in detail how you arrived to the answer.

Source of Capital	Target market Proportions
Long-term debt	20%
Preferred Stock	10
Common stock equity	70

- Debt: The firm can sell a 12-year, $1,000 par value, 7 percent bond for $960. A flotation cost of

2 percent of the face value would be required in addition to the discount of $40.

- Preferred Stock: The firm has determined it can issue preferred stock at $75 per share par value. The stock will pay a $10 annual dividend. The cost of issuing and selling the stock is $3 per share.

- Common Stock: A firm's common stock is currently selling for $18 per share. The dividend expected to be paid at the end of the coming year is $1.74. Its dividend payments have been growing at a constant rate for the last four years. Four years ago, the dividend was $1.50. It is expected that to sell, a new common stock issue must be underpriced $1 per share in floatation costs. Additionally, the firm's marginal tax rate is 40 percent.

Please show the formula and the work for the below:

1) The firm's before-tax cost of debt is ________.

2) The firm's after-tax cost of debt is ________.

3) The firm's cost of preferred stock is ________.

4) The firm's cost of a new issue of common stock is ________. )

5) The firm's cost of retained earnings is ________.

6) The weighted average cost of capital up to the point when retained earnings are exhausted is ________.