Given a risk$-$free pretax discount rate of $12\%,$ an inflation rate of $3\%,$ a risk premium of $2\%$ and a tax rate of $22\%,$ calculate the real after$-$tax discount rate.

Group of answer choices

$12\%$

$9\mathrm{.}36\%$

$7\mathrm{.}69\%$

$10\mathrm{.}92\%$