title: How can I turn an array of keys into an array of values?
body: <p>I have a hash like</p>
  
  <pre><code>hash = { 'burger': 2, 'kebab': 5, 'pizza': 10 }
  </code></pre>
  
  <p>and I have an array of its keys like</p>
  
  <pre><code>['burger', 'burger', 'pizza']
  </code></pre>
  
  <p>How would I create an array of the corresponding values? Would <code>inject</code> method be the best method to sum value array together?</p>