using System;

​

public class Program

{

    public static void Main()

    {

        var invoice = new Invoice();

        Console.WriteLine(invoice.GetInvoiceDiscount(100, InvoiceType.ProposedInvoice));

    }

}

​

public class Invoice

{

    public double GetInvoiceDiscount(double amount, InvoiceType invoiceType)

    {

        double finalAmount = 0;

        if (invoiceType == InvoiceType.FinalInvoice)

        {

            finalAmount = amount - 100;

        }

        else if (invoiceType == InvoiceType.ProposedInvoice)

        {

            finalAmount = amount - 50;

        }

​

        return finalAmount;

    }

}

​

public enum InvoiceType

{

    FinalInvoice,

    ProposedInvoice

};