title: What's happening with this expression? b = a + (a = a + 5)
body: <pre><code>a = 5
  b = a + (a = a + 5)
  </code></pre>
  
  <p>result b = 15</p>
  
  <p>Why the first 'a' do not changes after that (a = a + 5)? But why second one changes? What exactly is happening here by steps? </p>