title: How to do math in a Django template?
body: <p>I want to do this:</p>
  
  <pre><code>100 - {{ object.article.rating_score }} 
  </code></pre>
  
  <p>So for example, the output would be <code>20</code> if <code>{{ object.article.rating_score }}</code> equaled <code>80</code>.</p>
  
  <p>How do I do this at the template level? I don't have access to the Python code.</p>