title: jquery find link by rel
body: <p>i have some links in my page</p>
  
  <pre><code>&lt; a class="Qlink" rel="20;5" href="javascript:void(0);"&gt;5&lt;/a&gt;
  &lt; a class="Qlink" rel="21;6" href="javascript:void(0);"&gt;6&lt;/a&gt;
  &lt; a class="Qlink" rel="22;7" href="javascript:void(0);"&gt;7&lt;/a&gt;
  </code></pre>
  
  <p>i do some ajax call and get the first number on the rel attribute(exp. 20)</p>
  
  <p>how do i can change the class of link (the first in my exp.)</p>