title: Math equation for scaling number between two limits not starting at 0?
body: <p>For example, I have a number between 1~100 and I need to scale it to be between 20~80.  </p>
  
  <p>Examples:</p>
  
  <pre><code>1 scales to 20
  100 scales to 80
  50 scales to 50
  </code></pre>