title: Sum third element of each list in a list
body: <p>I currently have a list like:</p>
  
  <blockquote>
    <p>((map 9 <strong>150</strong>) (compass 13 <strong>35</strong>) (water 150 <strong>240</strong>) (sandwich 50 <strong>16</strong>) (rope 50 <strong>49</strong>))</p>
  </blockquote>
  
  <p>I am trying to loop through this list get the values in bold and give a total of these value. I have been looking at car and cdr but I can't seem to get these values. Is there a simple way to do this?</p>