<?php
$array = array(
    array(
        'xp_required' => 150,
        'level' => 1
    ),
    array(
        'xp_required' => 225,
        'level' => 2
    ),
    array(
        'xp_required' => 337,
        'level' => 3
    ),
    array(
        'xp_required' => 566,
        'level' => 4
    ),
    array(
        'xp_required' => 846,
        'level' => 5
    ),
    array(
        'xp_required' => 1274,
        'level' => 6
    ),
    array(
        'xp_required' => 1911,
        'level' => 7
    ),
    array(
        'xp_required' => 2866,
        'level' => 8
    ),
    array(
        'xp_required' => 4299,
        'level' => 9
    ),
    array(
        'xp_required' => 6449,
        'level' => 10
    )
);
$current_xp = 155;
foreach( $array as $reqs ){
    if( $current_xp > $reqs['xp_required'] ){
        $level = $reqs['level'];
    }
}
echo 'You are at ' ,$level;

?>