致命错误 - 不支持操作数类型，我继续收到以下错误，我想知道如何解决它

Question

I Keep getting the following error and I was wondering on how to fix it?

fatal-error-unsupported-operand-types error occurs

Please any one help me out:

if($_REQUEST['cityCode'] != ''){ 
    $_SESSION['Cri_locations'] = $_REQUEST["s"];
    $_SESSION['Cri_DateFrom'] = $_REQUEST["startDate"];
    $_SESSION['Cri_DateTo'] = $_REQUEST["endDate"];
    $what_to_search_id =str_replace("AREA-","",$_REQUEST["cityCode"]);
    $total_adults =0;
    $total_childs =0;
    $child_ages =0;
    $no_of_room =0;
    for($i=1;$i<=$_REQUEST["Cri_noofRooms"];$i++){ 
        $check_adults =$_REQUEST['adults-r'.$i.''];
        if($check_adults>0){
          $adults =$_REQUEST['adults-r'.$i.''];
          $childs =$_REQUEST['childs-r'.$i.''];
          $childAge =$_REQUEST['childAge-r'.$i.''];
          $packs_arr[] =array('adults'=>$adults,'childs'=>$childs,'childAge'=>$childAge);
          $total_adults =$total_adults+$adults;
          $total_childs =$total_childs+$childs;
          $child_ages =$child_ages+$childAge;//fatal-error-unsupported-operand-types accours here pls help 
          $no_of_room =$no_of_room+1;
        }
    }