title: Subtract one DateTime from another and return days
body: <p>I have 2 DateTime objects. One which represents 2 days from now and the other which represents 2 days and 6 months from now.</p>
  
  <p>I need to be able to count the number of days between these two dates to display to users which dates they can book on.</p>
  
  <p>I have calculated the two dates successfully but I am struggling finding a way to subtract them and return the difference in days.</p>