"The spot exchange rate is $\mathrm{.}05$ usd$/$mxn$,$ the interest rate free of credit risk in Mexico is $5\%$ while that of the USA is $\mathrm{.}1\%.$ Calculate the one year's call price if the strike price is $20\mathrm{.}1$ mxn$/$usd and the volatility is $20\%."$