function ChangeNow(welke,aantal){
	if(document.getElementById){
		for(var i=1;i<=aantal;i++){
			document.getElementById('sub'+i).style.visibility = 'hidden';
			document.getElementById('sub'+i).style.display = 'none';
		}
		document.getElementById('sub'+welke).style.visibility = 'visible';
		document.getElementById('sub'+welke).style.display = 'block';
	}
}