title: How To Get Array Sum
body: <p>I have 2 arrays.</p>
  
  <pre><code>$fruits = [
      'mango' =&gt; 20,
      'apple' =&gt; 30,
      'orange' =&gt; 10,
      'banana' =&gt; 5,
  ];
  
  $purchased = ['mango','banana'];
  </code></pre>
  
  <p>How do I get the sum of the values on the <code>$fruits</code> array that are only available on the <code>$purchased</code> array? That is get the sum = 25</p>