title: Date comparison - How to check if 20 minutes have passed?
body: <p>How to check if 20 minutes have passed from current date?</p>
  
  <p>For example: </p>
  
  <pre><code>var start = DateTime.Now;
  var oldDate = "08/10/2011 23:50:31"; 
  
      if(start ??) {
       //20 minutes were passed from start
      }
  </code></pre>
  
  <p>what's the best way to do this?
  Thanks :)</p>