function toggleAnswer(id){
	var answer = document.getElementById('answer_'+id);
	
	//find all answers and close them
	var arrayAnswers = getAnswerElements();
	var i;
	for ( i = 0; i < arrayAnswers.length; i++ ){
		//close them all
		arrayAnswers[i].style.display = 'none';
	}	
	
	answer.style.display = 'block';
	
	//TODO hide all other open answers
}

function getAnswerElements () {
  var all = document.all ? document.all : document.getElementsByTagName("div");
  var elements = new Array();
  for (var e = 0; e < all.length; e++)
    if (all[e].id.substring(0,7) == 'answer_') elements[elements.length] = all[e];
  return elements;
}