Calculate the weighted average cost of capital (WACC) for Company GHI, which has a cost of equity of 12%, a cost of debt of 6%, and a corporate tax rate of 35%. The company's target capital structure consists of 70% equity and 30% debt. Explain the weighted average cost of capital (WACC) as a measure of a company's cost of capital, indicating the average rate of return required by investors to finance its operations. Discuss the significance of WACC in investment analysis, capital budgeting decisions, and its implications for business valuation and cost of capital estimation.