title: Add values in a column if value in another column is true
body: <pre><code>Column1 Paid    Amount
  A       Yes     $45
  B       No      $15
  C       Yes     $30
  D       Yes     $60
  E       No      $30
  F       No      $25
  </code></pre>
  
  <p>What I want to do is add up all the values in column 3 as long as there corresponding value in the "Paid" column is "Yes". </p>
  
  <p>Essentially so that I have total amount for how much I have currently been paid. So the example should have an effective output a value of $135.</p>