how to get before 2 hrs time in php code example

Example: get 2 hrs before data in php

//set timezone
date_default_timezone_set('Asia/Kolkata');

//set an date and time to work with
$start = '2014-06-01 14:00:00';
echo date('Y-m-d H:i',strtotime('+1 hour +20 minutes',strtotime($start)));