What is the after$-$tax cost of debt for a company in the $42\%$ tax bracket with a bond outstanding at $13\%$ maturity? What if the tax bracket is $46\%?$ What if the tax bracket is $38\%?$

What is the cost of preferred stock if the annual dividend is $$8\mathrm{.}75,$ stock price is $$12,$ and the flotation cost is $$3?$ How is the cost of preferred stock impacted if the annual dividend increases to $$9?$ What if the annual dividend decreases to $$8\mathrm{.}50?$