From the differential formulas $(9\mathrm{.}3\mathrm{.}14)$ and $(9\mathrm{.}3\mathrm{.}15)$ for the stock and discounted exchange rate in terms of the Brownian motions under the domestic risk$-$neutral measure, derive the differential formulas $(9\mathrm{.}3\mathrm{.}22)$ and $(9\mathrm{.}3\mathrm{.}23)$ for the redenominated money market account and stock discounted at the foreign interest rate and written in terms of the Brownian motions under the foreign risk$-$neutral measure.