program CurrencyConverter;
var
choice: integer;
amount, rate, convertedAmount: real;
begin
writeln('Currency Converter');
writeln('1 - Convert from USD to RUB');
writeln('2 - Convert from RUB to USD');
write('Enter your choice: ');
readln(choice);
write('Enter amount: ');
readln(amount);
write('Enter current exchange rate: ');
readln(rate);
case choice of
1: begin
convertedAmount := amount * rate;
writeln('Amount in RUB: ', convertedAmount:0:2);
end;
2: begin
convertedAmount := amount / rate;
writeln('Amount in USD: ', convertedAmount:0:2);
end;
else
writeln('Invalid choice');
end;
end.

Пример использования программы:

Currency Converter
1 - Convert from USD to RUB
2 - Convert from RUB to USD
Enter your choice: 1
Enter amount: 100
Enter current exchange rate: 70
Amount in RUB: 7000.00