title: Weighted union rule
body: <p>Can someone check with me if I'm using the rule right in the last step (7)?</p>
  
  <p>UPDATE:</p>
  
  <p><strong>Numbers inside the parentheses are the number of elements (weight(?)) of each set that takes part in the Union.</strong> Uppercase letters are names of sets.</p>
  
  <p>As I understand this: we are using as our rank the number of elements? This is getting confusing, each one is using different terms for the same stuff.</p>
  
  <p>We have Unions:</p>
  
  <ol>
  <li>U(1,2,A)</li>
  <li>U(3,4,B)</li>
  <li>U(A,B,C)</li>
  <li>U(5,6,D)</li>
  <li>U(7,8,E)</li>
  <li>U(D,C,F)</li>
  <li>U(E,F,G)</li>
  </ol>
  
  <p><img src="https://i.stack.imgur.com/fCCoS.jpg" alt="enter image description here"></p>