function hideAnswer(id){
	if(document.getElementById(id).style.display=="none"){

		MagicId=document.getElementById("last_actived").value;
		document.getElementById(MagicId).style.display="none";
		document.getElementById("last_actived").value=id;

		document.getElementById(id).style.display="block";

	}else{
		document.getElementById(id).style.display="none";
	}
}