Need help with a book exercise! Javascript!

[ApDev]

1. The user is visiting Thailand. He or she has 65 U.S. dollars. Tell the user how many Thai baht that amounts to. Display an image of the Thai flag on the same page.
   
   
2. My code:
   <script>
   var baht = 33.42;
   var usd = 65 * baht;
   var str1 = "$65 ="
   usd = usd.toString(usd);
   str1 = str1.concat(usd)
   str1 = str1.concat("baht");
   alert(str1);
   document.write("65 = " + "65 * 33.42" + "<br/>");
   </script>