title: More efficient jquery for bill estimator
body: <p>I'm working on a calculator to find extra charges based on bill cost. The basic idea is that if the bill is less than $200, there are set charges for different increments. If the bill is over $200, then the charge goes up 1.12 for every $50 of increase. I ended up manually writing out all the possibilities up to $400, but I'm not sure how high the bills can go, and regardless I feel like there has to be a better way to do this, especially the part where the value is being updated within each IF statement. </p>
  
  <pre><code>&lt;fieldset&gt;&lt;label&gt;Costs&lt;/label&gt;&lt;input type="text" id="systemSize"/&gt;&lt;/fieldset&gt;
  
  &lt;fieldset&gt;&lt;label&gt;Average bill amount &lt;input type="text" id="billAmount"/&gt;&lt;/fieldset&gt;
  
  &lt;p class="submit" id="submit"&gt;SUBMIT&lt;/p&gt;
  
  if(billAmount){
          if(billAmount&lt;50){
              alert ("Bill amount is too low");
          }
  
          if(billAmount&gt;=50 &amp;&amp; billAmount &lt;75){
              systemSizeNew = ("2.8");
              $("#systemSize").val(systemSizeNew);
          }
  
          if(billAmount&gt;=75 &amp;&amp; billAmount &lt;100){
              systemSizeNew = ("3.36");
              $("#systemSize").val(systemSizeNew);
          }
  
          if(billAmount&gt;=100 &amp;&amp; billAmount &lt;150){
              systemSizeNew = ("4.3");
              $("#systemSize").val(systemSizeNew);
          }
  
          if(billAmount&gt;=150 &amp;&amp; billAmount &lt;200){
              systemSizeNew = ("5.32");
              $("#systemSize").val(systemSizeNew);
          }
  
          if(billAmount&gt;=200 &amp;&amp; billAmount &lt;250){
              systemSizeNew = ("6.44");
              $("#systemSize").val(systemSizeNew);
          }
  
          if(billAmount&gt;=250 &amp;&amp; billAmount &lt;300){
              systemSizeNew = ("7.56");
              $("#systemSize").val(systemSizeNew);
          }
  
          if(billAmount&gt;=300 &amp;&amp; billAmount &lt;350){
              systemSizeNew = ("8.68");
              $("#systemSize").val(systemSizeNew);
          }
  
          if(billAmount&gt;=350 &amp;&amp; billAmount &lt;400){
              systemSizeNew = ("9.80");
              $("#systemSize").val(systemSizeNew);
          }
         }
  </code></pre>