YUI({combine: true, timeout: 10000}).use("io",
  function(Y) {
    var div = Y.Node.get('#contactresponse');
    Y.on('io:success', function(ioId, o) { if(o.responseText !== undefined) { div.set("innerHTML", o.responseText); } });
    Y.on('io:failure', function(ioId, o) { div.set("innerHTML", "Something's broken"); });
    function makeRequest(){
      var datastr = "a="+Y.Node.get("#na").get("value")+"&b="+Y.Node.get("#nb").get("value")+"&c="+Y.Node.get("#nc").get("value");
      Y.io("/app/contact.php", {method: "POST", data: datastr} );
      return false;
    }
    Y.on("click", makeRequest, "#equals");
  }
);