Forgetting something with my functions

I wrote this java script code for a program that will convert an inputed temperature to celsius. I have it all done, but one thing seems to be wrong because when I type in 78 dg. fahrenheit, it converts it to 46 dg. celsius and that isn’t right. I want my code to take the users input # and subtract 32 from it, and then multiply that number by .55? Here is my code, if someone can see what I did wrong, please give me a tip. I am just missing one thing and it is good to have some fresh eyes look at it. Thanks alot.

boebarl1

<script type = “text/javascript”>

var fahrTemp;

var fahrTemp = window.prompt( “Please enter the Current Temperature in fahrenheit.” );

document.writeln( “<h1> The current Temperature is " + fahrTemp + " Degrees Fahrenheit.</h1>” );

document.writeln( “<h2> Click the button below to see the Current Temperature in Celsius.</h2>” );

function popup(){

function conversion( x ) {
return fahrTemp - 32;
function run ( y ){ return fahrTemp * .55; }
}

alert(“The current Temperature is " + conversion( fahrTemp) + " Degrees Celsius” )

}
</script>
</head>
<body>
<input type=“button” onclick=“popup()” value=“Temperature Conversion” >
</body>
</html>