javascript calculate

by Rich Costello

HTML

<input id="a1" type="text" />
<input id="a2" type="text" onblur="calculate()"  />
<input id="a3" type="text" name="total_amt" />

JavaScript

calculate = function()
{
    var resources = document.getElementById('a1').value;
    var minutes = document.getElementById('a2').value; 
    document.getElementById('a3').value = parseInt(resources)-parseInt(minutes);
     
   }