using System;

public class Program

{

    public static void Main()

    {

        var payment=new Payment();

        payment.Amount = 400;

        int refundRequestAmount = 65;

        var fee = payment.Amount - (decimal)refundRequestAmount/100;

        Console.WriteLine(fee);

    }

}

​

public class Payment {

    public Decimal Amount {get;set;}

}