title: Checking if a Ruby array's elements are included in another array
body: <p>I am trying to compare two Ruby arrays to verify that all of the first array's elements are included in the second one. (The reverse isn't needed.)</p>
  
  <p>For example:</p>
  
  <pre><code>a = ["hello", "goodbye"]
  b = ["hello", "goodbye", "orange"]
  </code></pre>
  
  <p>This should return true.</p>
  
  <p>However, I can't figure out a method that will allow me to do this. Any help would be appreciated!</p>