QUESTION $7$

An all equity firm has a cost of capital of $9\mathrm{.}1$ percent. The firm is considering switching to a debt$-$equity ratio of $1\mathrm{.}90$ with a pretax cost of debt of $5\mathrm{.}4$ percent. What will the firm's cost of equity be if the firm makes the switch? The tax rate is $25\%.$