The proportion of equity is 10,080,000/18,000,000=60%.
We do not use the floatation cost here, since retained earnings are internally generated and not to be raised.
WACC = Cost of Debt X proportion of debt + Cost of Preferred Stork X Proportion of preferred stork + Cost of equity X Proportion of equity
WACC = 6.92% X 0.34+ 8.36% X 0.06+ 14.8% X 0.60
WACC = 11.73%