Greshak Corp. is analyzing its optimal capital structure. Currently, Greshak's capital structure includes 20% debt and the company is planning to double its debt capitalization. Assume that the current risk-free rate is 4.00% and the equity risk premium is 6.25%. If the company's cost of equity, which is based on the CAPM, is 12.50% and its tax rate is 40.00%, what would Greshak's estimated cost of equity (rounded) be if the company were to change its capital structure as indicated above? Make sure you use at least four (4) decimal places in calculations and