function sichtbarkeit(id) {
	var a = 'a' + id;
	var b = 'b' + id;
	var c = 'c' + id;
	if(document.getElementById(a).style.display == "none") {
		document.getElementById(a).style.display = "inline";
	} else {
		document.getElementById(a).style.display = "none"
	}
	if(document.getElementById(b).style.display == "none") {
		document.getElementById(b).style.display = "inline"
	} else {
		document.getElementById(b).style.display = "none"
	}
	if(document.getElementById(c).style.display == "none") {
		document.getElementById(c).style.display = "inline"
	} else {
		document.getElementById(c).style.display = "none"
	}
}