function addEvent(els, type, func) {
	if(!(els instanceof Array)) els = [els];
	for(var i=0, n=els.length; i<n; ++i) {
		if(els[i].addEventListener) els[i].addEventListener(type, func, false);
		else els[i].attachEvent("on"+type, func);
	}
}

String.prototype.trim = function() {
	return this.replace(/^\s+/, "").replace(/\s+$/, "");
};

var price = document.getElementById("price");
var current = document.getElementById("current");
var proposed = document.getElementById("proposed");
var increase = document.getElementById("increase");

addEvent(
	[price],
	"keyup",
	function(e) {
		var vprice = price.value.trim();
		var nprice = vprice*1;
		if(vprice=="" || isNaN(nprice)) {
			current.value = proposed.value = increase.value = "";
			return;
		}
		current.value = Math.round(nprice * .009);
		proposed.value = Math.round(nprice * .012);
		increase.value = proposed.value - current.value;
	}
);