You were hired as a consultant to Giambono Company, whose target capital structure is $40\%$ debt, $15\%$ preferred, and $45\%$ common equity. The after$-$tax cost of debt is $6\mathrm{.}00\%,$ the cost of preferred is $7\mathrm{.}50\%,$ and the cost of retained earnings is $11\mathrm{.}50\%.$ The firm will not be issuing any new stock. What is its WACC?

Question $9$ options:

$8\mathrm{.}70\%$

$8\mathrm{.}87\%$

$7\mathrm{.}92\%$

$7\mathrm{.}66\%$

$6\mathrm{.}70\%$