function showOrHideAnswer(id) {
	pic_id_show = 'item_' + id + '_show';
	pic_id_noshow = 'item_' + id + '_noshow';
	ans_id = 'item_' + id + '_ans';
	
	//show it
	if (document.getElementById(ans_id).style.display == 'none') {
		document.getElementById(pic_id_noshow).style.display = 'none';
		document.getElementById(pic_id_show).style.display = 'block';
		document.getElementById(ans_id).style.display = 'block';
	} 
	//hide it
	else {
		document.getElementById(pic_id_noshow).style.display = 'block';
		document.getElementById(pic_id_show).style.display = 'none';
		document.getElementById(ans_id).style.display = 'none';
	}
}