title: PHP7: Combine two arrays, where one is key and second is value (integer), sum values for duplicate keys
body: <p>I have 2 arrays in PHP7:</p>
  
  <pre><code>$Array1 = ["bus","bus","int"];
  $Array2 = [2,18,10];
  </code></pre>
  
  <p>Where $Array1 is <b>key</b> and $Array2 is <b>value</b> for each index.
  <br />I need to combine both and sum values for duplicate keys, e.g. get following output:</p>
  
  <pre><code>$Array3 = ["bus" =&gt; 20, "int" =&gt; 10];
  </code></pre>
  
  <p>Thank you!</p>