$9-16.($Weighted average cost of capital$)$ The capital structure for the Carion Corporation is provided here. The company plans to maintain its debt structure in the future. If the firm has a $5\mathrm{.}5$ percent after$-$tax cost of debt, a $13\mathrm{.}5$ percent cost of preferred stock, and an $18$ percent cost of common stock, what is the firm$$s weighted average cost of capital?