HELP!! project due Monday night and my teacher is not emailing me back.
I can not get any of my math functions to work....

*/ I am calling this before main*/
double russianRuble = 31.168;
float northKoreanWon = 135;
double chineseYuan = 6.832;
float cubanPeso = 1;
double ethiopianBirr = 9.09;
double thaiBaht = 34.4;
double canadianDollars = 1.1137;
double tunisianDinar = 1.3585;
double egyptianPound = 5.6275;
//===============================================================

float calcExchangeAmt(char choice, float money, float exchange, string currencyChoice)
{
switch (choice) {
case 'A': exchange = money * russianRuble; currencyChoice = "Rubles";
break;
case 'B': exchange = money * northKoreanWon; currencyChoice = "Wons";
break;
case 'C': exchange = money * chineseYuan; currencyChoice = "Yuan";
break;
case 'D': exchange = money * cubanPeso; currencyChoice = "Pesos";
break;
case 'E': exchange = money * ethiopianBirr; currencyChoice = "Birrs";
break;
case 'F': exchange = money * thaiBaht; currencyChoice = "Baht";
break;
case 'G': exchange = money * canadianDollars; currencyChoice = "Canadian Dollars";
break;
case 'H': exchange = money * tunisianDinar; currencyChoice = "Dinars";
break;
case 'I': exchange = money * egyptianPound; currencyChoice = "Egyptian Pounds";
break;
}
return exchange;
}