title: Subtract (-) 2 Text Labels from each other to get result
body: <p>Well, I've tried it with ToInt, ToString, and I'm out of options.
  I'm trying to substract 2 Label Texts from each other. (Those contains numbers from RSS)</p>
  
  <p>What I have at the moment:</p>
  
  <pre><code>        lblOldID.Text = nodeChannel["oldid"].InnerText;
          lblNewID.Text = nodeChannel["newid"].InnerText;
  </code></pre>
  
  <p>So let's say oldid contains "500" and newid "530".</p>
  
  <p>But for some reason, I can't substract (-) them.
  What I want:</p>
  
  <pre><code>      lblResultID.Text = lblOldID.Text - lblNewID.Text;
  </code></pre>
  
  <p>Example: Result = 530 - 500</p>
  
  <p>So how is that possible?</p>