can you help me undertand this concept? Thank you!!

Golden Gate Construction Associates, a real estate developer and building contractor in San Francisco, has two sources of long-term capital: debt and equity. The cost to Golden Gate of issuing debt is the after-tax cost of the interest payments on the debt, taking into account the fact that the interest payments are tax deductible. The cost of Golden Gate's equity capital is the investment opportunity rate of Golden Gate's investors, that is, the rate they could earn on investments of similar risk to that of investing in Golden Gate Construction Associates. The interest rate on Golden Gate's $93 million of long-term debt is 11 percent, and the company's combined federal and state income tax rates amount to 30 percent. The cost of Golden Gate's equity capital is 15 percent. Moreover, the market value (and book value) of Golden Gate's equity is $186 million. Required: Calculate Golden Gate Construction Associates' weighted-average cost of capital, Note: Round your answer to 1 decimal place. (i.e., .123 should be entered as 12.3)