PHP - Array (Loop)

<?php

$name = $_POST["name"];
$studentid = $_POST["studentid"];
$java = $_POST["java"];
$web = $_POST["web"];
$cpp = $_POST["cpp"];
$total = $java + $web + $cpp;
$average = $total / 3;

echo "Student Name : $name <br>";
echo "Student ID :  $studentid <br><br>";
echo "Total is : $total <br>";
echo "Average is : $average <br><br>";

$num = array("Java :"=>"$java","Web :"=>"$web","C++ :"=>"$cpp");

foreach($num as $x=>$x_value) {

    if($num[$x] >= 90){
        echo $x . " A";
        echo "<br>";
    }
    else if($num[$x] >= 80){
        echo $x . " B";
        echo "<br>";
    }
    else if($num[$x] >= 70){
        echo $x . " C";
        echo "<br>";
    }
    else if($num[$x] >= 60){
        echo $x . " D";
        echo "<br>";
    }
    else{
        echo $x . " F";
        echo "<br>";
    }

}

?>