using System;

public class Program

{

    public static void Main()

    {

        var startdate="10/06/2020";  //msg date

        var enddateForFileName="09/23/2020";

        var startdateForFileName="";

        TimeSpan  Totalskipday = Convert.ToDateTime(startdate).Subtract(Convert.ToDateTime(enddateForFileName));

         var ans =  (int) Totalskipday.TotalDays;

        ans=(ans/7)*7;

        enddateForFileName = Convert.ToDateTime(enddateForFileName).AddDays(1).ToString("MM/dd/yyyy");

         startdateForFileName = Convert.ToDateTime(enddateForFileName).AddDays(ans).ToString("MM/dd/yyyy");

                                                enddateForFileName = Convert.ToDateTime(startdateForFileName).AddDays(6).ToString("MM/dd/yyyy");

        Console.WriteLine(startdateForFileName);

                Console.WriteLine(enddateForFileName);

​

    }

}