title: Add -30 minutes to date
body: <p>I have this function </p>
  
  <pre><code>$timetable-&gt;start_time = $row{'deadline_time'} ? date('H:i', strtotime($row{'deadline_time'})) : ''; // start_time : Must be 24 hour format. For example: 18:00
  $timetable-&gt;end_time = $row{'deadline_time'} ? date('H:i', strtotime($row{'deadline_time'})) : ''; // end_time : Must be 24 hour format. For example: 20:30
  </code></pre>
  
  <p>And i need to add -30 minutes to that time. How can I add it? </p>
  
  <p>@UPDATE
  I just update the code..
  So the code is the same for start and end I just need to add -30 mins to the start. :)</p>