static void Main(string[] args)
{
// Using the new CalculateDiscount method
NewOrder newOrder = new NewOrder();
decimal newDiscount = newOrder.CalculateDiscount(100, 20);
Console.WriteLine("First price: {0}", newDiscount);
Order order = newOrder;
decimal discount = order.CalculateDiscount(100, 20);
Console.WriteLine("Second price: {0}", discount);
}