$4.$ A firm has $80$ bonds outstanding that are selling at their par value of Rs$.1,000$ each. Bonds with similar characteristics are yielding a pretax $8\mathrm{.}6$ percent. The firm also has $4,000$ shares of equity stock outstanding. The stock has a beta of $1\mathrm{.}1$ and sells for Rs$.40$ a share. The RBI $10$ year T$-$bill is yielding $4$ percent, the market risk premium is $8$ percent, and the firm's tax rate is $21$ percent. What is the firm's weighted average cost of capital, assuming its earnings are sufficient to classify all interest as a tax$-$deductible expense