function _(title) {
  return document.getElementById(title);
}

function changeStatus(id) {
  img_name    = 'img_' + id;
  answer_name = 'answer_' + id;
  
  if (_(answer_name).style.display == 'none') { 
    _(img_name).src = 'images/minus.gif';
    _(answer_name).style.display = 'block';
    /*_(answer_name).style.width = '450px';*/
  } else {
    _(img_name).src = 'images/plus.gif';
    _(answer_name).style.display = 'none';
  }
}