title: Package 'php5-gd' has no installation candidate
body: <p>"PHP module gd: Missing" I received such an error. and I'm trying to install <code>php5-gd</code>.</p>
  
  <pre><code>apt-get install php5-gd
  </code></pre>
  
  <p>I am using Ubuntu 16.10 and PHP version 7. I made all the updates.</p>
  
  <p>When I tried to install <code>php5-gd</code>, I got an error like below.</p>
  
  <pre><code>Reading package lists... Done
  Building dependency tree       
  Reading state information... Done
  Package php5-gd is not available, but is referred to by another package.
  This may mean that the package is missing, has been obsoleted, or
  is only available from another source
  
  E: Package 'php5-gd' has no installation candidate
  </code></pre>