Foriegn currency to another foriegn currency exchange calculation issue

Hi all,
I cannot get my foreign currency to exhange to another foreign currency.  We are supposed to use two switch cases statements. We were advised to use a formula that takes the 1st foreign currency to USD and then to another foriegn currency which will allow the exchange from one FC to FC. Here is what I have so far.  I've racked my brain on this all week and it's due tomorrow at 6p mst.  Nothing like waiting until the last minute!  Any help would be appreciated!  I just need to keep it simple! Thanks so much!
Susan =)

/*6/19/06 POS370 Susan Johnson Individual Assignment 3 of 3:
* Week 1 - Find 5 foreign currencies and display conversion in us dollars
* Week 2 - Offer the user a choice of which foreign currency and how much to exchange into USD
* Week 3 - Change any currency to any currency. Use two case statements one is from foriegn currency to USD.*/

#include <stdio.h>

main ()
{
float peso = 0.0885426;
float yen = 0.00895015;
float pound = 1.8775;
float can = 0.910415;
float ruble = 0.0374186;
float amt = 0.0;
float usd = 0.0;
float total = 0.0;
int choice1;
int choice2;
int promptUSD;
int promptXFC;
int x = 0;

      printf("\nForiegn Currency Conversion Table\n");
      printf("\n\t1: Mexican peso");
      printf("\n\t2: Japanese yen");
      printf("\n\t3: British pound");
      printf("\n\t4: Canadian dollar");
      printf("\n\t5: Russian ruble");

   while (x == 0)
   {/*begin while loop*/
      printf( "\n\nChoose a foreign currency using 1 - 5: ");
      scanf ( "%d", &choice1);
      
      if (choice1 >= 1 && choice1 <= 5)
      {/*begin if statement*/
            printf( "\n\nEnter the amount to be converted: ");
               scanf( "%f", &amt);
      
            switch (choice1)
                  {/*begin switch/case*/      
        
                    case 1:
                             usd = peso*amt;
                             break;
                     case 2:
                              usd = yen*amt;
                              break;
                     case 3:
                              usd = pound*amt;
                              break;
                     case 4:
                              usd = can*amt;
                                    break;
                     case 5:
                              usd = ruble*amt;
                              break;  
               default:
                        printf("\nYou did not choose a valid currency 1 -5:\n");
                  
          
      }/* end if*/
      
      }/* end switch/case*/
      
      printf( "\n\nUse 1 - 5 again to exchange your amount to another currency: ");
      scanf ( "%d", &choice2);
      
            switch (choice2)
                  {/*begin switch/case*/      
        
                    case 1:
                             usd=amt/peso;
                             printf("\n\nYou entered $%.2f which equals $%.2f pesos\n",amt,usd);
                             break;
                     case 2:
                              usd = amt/yen;
                              printf("\n\nYou entered $%.2f which equals $%.2f Yen\n", amt,usd);
                              break;
                     case 3:
                              total = pound*amt;
                              printf("\n\nYou entered $%.2f which equals $%.2f Pounds\n", amt,usd);
                              break;
                     case 4:
                              total = can*amt;
                              printf("\n\nYou entered $%.2f which equals $%.2f CAD\n", amt,usd);
                              break;
                     case 5:
                              total = ruble*amt;
                              printf("\n\nYou entered $%.2f which equals $%.2f rubles\n", amt,usd);
                              break;  
                     default:
                              printf("\nYou did not choose a valid currency 1 - 5:\n");
          
                  
            }/*end switch/case*/
            
      
      
      printf("\n\nWould you like to exchange your amount to another currency? 1 for yes, 2 for no: ");
      scanf("%d", &promptUSD);

            if (promptUSD == 2)
                  {/*begin if statement*/
                   x=1;
                    }/*end if statement*/      
 }/*end while loop*/      
                   printf("\n\nHave a nice day!");

             
        
   //else }
 
   //       printf("you entered and incorrect number, please choose from 1-5");

getchar();

}/*end main program*/