title: Subtract two lists in Python without using classes
body: <p>I have two numeric lists, <strong>a</strong>, <strong>b</strong> that I am trying to subtract like this; <strong>b - a</strong>. </p>
  
  <p>I want this to be easy for a beginner to understand so I don't want to import classes or libraries.</p>
  
  <p><strong>This is what I have tried, and it works:</strong></p>
  
  <pre><code>a = [420, 660, 730, 735] 
  b = [450, 675, 770, 930]   
  i = 0
  j = len(a)
  difference = []
  
  while i &lt; j:
      difference.append(b[i] - a[i])
      i += 1
  print (difference) 
  &gt;&gt;[30, 15, 40, 195]    **the correct result**
  </code></pre>
  
  <p>However, there must be a simpler way of doing this without importing classes or libraries that I am missing. </p>