The market value of Nvidia Corporation's common stock is $$20$ million, and the market value of its risk$-$free debt is $$30$ million. The beta of the company's common stock is $2\mathrm{.}50,$ and the market risk premium is $10\%.$ If the Treasury bill rate is $3\%,$ what is the company's cost of capital? $($Assume no taxes.$)$

$15\mathrm{.}5\%$

$13\mathrm{.}0\%$

$10\mathrm{.}0\%$

$11\mathrm{.}5\%$