title: Search a list inside a list in Linq
body: <p>I have a list of Meeting classes which each class include another class of strings, I want to search each Meeting class if its list of strings contains specific key. If it does, then return this meeting</p>
  
  <p>I wrote the code below, but it returns a list of strings. PS: _meetings is a list</p>
  
  <pre><code>        List&lt;Meeting&gt; meetings = _meetings.SelectMany(m =&gt; m.AuthinticatedUsers_Id.Where(s =&gt; s == App.user.Id)).ToList();
  </code></pre>