title: Subtract Time String in PHP
body: <p>Say I have the following as a string:</p>
  
  <p>$timeLeft = 00:02:30</p>
  
  <p>I want to be able to subtract 1 second, turning it into 00:02:29.</p>
  
  <p>I have tried</p>
  
  <p>$timeLeft - 1;</p>
  
  <p>But it does nothing.</p>
  
  <p>How can I make it so I can subtract seconds from a string?</p>