Write a PHP script to merge two arrays and sort them as numbers, in descending order ?

Program:-

<?php

    $a1=array(1,3,15,7,5);

    $a2=array(4,3,20,1,6);

    $num=array_merge($a1,$a2);

    array_multisort($num,SORT_DESC,SORT_NUMERIC);

    print_r($num);

?>

Output:-