Need to get number of days from Datetime

Question

Hi

I don't know where to start with the Datetimes.

I got a starting time Datetime and ending time Datetime.

this.Start = DateTime.Now;
this.End= Start.AddDays(length); //Lenght is an int from 0 to 40, days

I need to get the number of days left.
I need to subtract from End but how?

Thank you