- var_dump: documentation ( source)
- array_keys: documentation ( source)
- max: documentation ( source)
<?php
$array = array (
11 => 14,
10 => 9,
12 => 7,
13 => 7,
14 => 4,
15 => 6,
);
$maxs = array_keys($array, max($array));
var_dump($maxs);