Event.observe(window, 'load', function() {
  var golf_total = $('golf-total');
  var golf_total_amount = $('golf-total-amount');
  var golfer_golfing_members = $('golfer_golfing_members');
  var golfer_golfing_nonmembers = $('golfer_golfing_nonmembers');
  var golfer_holes_sponsored = $('golfer_holes_sponsored');
  var golfer_banquet_only = $('golfer_banquet_only');

  var price_member = 150;
  var price_nonmember = 175;
  var price_hole = 100;
  var price_banquet = 45;

  function update_total() {
    var total = 0;
    total += (golfer_golfing_members.value * price_member);
    total += (golfer_golfing_nonmembers.value * price_nonmember);
    total += (golfer_holes_sponsored.value * price_hole);
    total += (golfer_banquet_only.value * price_banquet);
    golf_total_amount.innerHTML = '$' + total + '.00';
    golf_total_amount.highlight();
  }

  Event.observe(golfer_golfing_members, 'change', update_total);
  Event.observe(golfer_golfing_nonmembers, 'change', update_total);
  Event.observe(golfer_holes_sponsored, 'change', update_total);
  Event.observe(golfer_banquet_only, 'change', update_total);
  
  update_total();
});