title: How to Calculate Bill Total JS
body: <p>I need to write a function called "calculateBillTotal".</p>
  
  <p>Given the pre tax and pre tip amount of a meal, "calculateBillTotal" returns the total amount due after tax and tip.</p>
  
  <p>Notes:<br/>
  * Assume that sales tax is 9.5% and tip is 15%.<br/>
  * Do NOT tip on the sales tax, only on the pre tip amount. <br/></p>
  
  <p>Here's my code:</p>
  
  <pre><code>function calculateBillTotal(preTaxAndTipAmount) {
    preTaxAndTipAmount - 9.5 + 15;
  
    return preTaxAndTipAmount;
  }
  
  var output = calculateBillTotal(20);
  console.log(output); // --&gt; it must be 24.9 but its return 20 instead.
  </code></pre>