title: Subtract two numbers in Linq from SQLServer
body: <p>I want to subtract two numbers from data base table 
  for condition : subtract of all times most less than 8</p>
  
  <pre><code>List&lt;Task&gt; ltask = ProjectDAL.GetAllTasks();
  </code></pre>
  
  <p>in DB I have Start_Time and End_time </p>
  
  <p>I want to subtract Start_Time from End_time for all end and start value inDB
  for ex : </p>
  
  <pre><code>Start_Time = 10
  End_time = 16 
  subtract = End_time - Start_Time = 6
  
  var subtract = ltask.Where(x =&gt;x.End_Time - x.Start_Time);
  </code></pre>
  
  <p>but is not working</p>