function showAnswer(prefix,number,total) {
	var i;
	var total;
	var number;
	var prefix;
	for (i=0;i<total;i++){
		document.getElementById(prefix + i).style.display = 'none';
		document.getElementById('q_' + i).className = '';
	}
	document.getElementById(prefix+number).style.display = 'block';
	document.getElementById('q_'+number).className = 'selected';
}