PHP - Fatal error: Unsupported operand types

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

This is the second time I got this error I fixed it the first time but for some reason I cant fix it the second time.

Fatal error: Unsupported operand types on line 103

Here is line 103.

$avg = (round($total_rating_points / $total_ratings,1));

Here is the full code below.

function getRatingText(){
    $dbc = mysqli_connect ("localhost", "root", "", "sitename");

    $page = '3';

    $sql1 = "SELECT COUNT(users_articles_id) 
             FROM articles_grades 
             WHERE users_articles_id = '$page'";

    $result = mysqli_query($dbc,$sql1);

    if (!mysqli_query($dbc, $sql1)) {
            print mysqli_error($dbc);
            return;
    }

    $total_ratings = mysqli_fetch_array($result);

    $sql2 = "SELECT grade_points 
             FROM grades 
             JOIN articles_grades ON grades.id = articles_grades.grade_id
             WHERE articles_grades.users_articles_id = '$page'";

    $result = mysqli_query($dbc, $sql2);

    if (!mysqli_query($dbc, $sql2)) {
            print mysqli_error($dbc);
            return;
    }

    while($row = mysqli_fetch_array($result)) {

        $trp[] = $row[0];
    }

    $total_rating_points = array_sum($trp);

    if (!empty($total_rating_points) && !empty($total_ratings)){
        $avg = (round($total_rating_points / $total_ratings,1));
        $votes = $total_ratings;
        echo $avg . "/10  (" . $votes . " votes cast)";
    } else {
        echo '(no votes cast)';
    }
}