title: Ruby string substitution
body: <p>Don't know what the term is called (substitution?), but in python if you type </p>
  
  <pre><code>num1 = 4  
  num2 = 2  
  print("Lucky numbers: %d %d" %(num1, num2))
  </code></pre>
  
  <p>You get "Lucky numbers: 4 2"</p>
  
  <p>How do I do this in ruby?</p>
  
  <p>Trying to do the above scenario, it works if I have one variable, but if I need to sub in multiple variables the parentheses aren't valid syntax.</p>