class Program
    {
        static void Main(string[] args)
        {
            List<CartLine> Lines = new List<CartLine>();
            Lines.Add(new CartLine() { ProductCode = "p1", Price = 6.5M, Name = "Product1" });
            Lines.Add(new CartLine() { ProductCode = "p1", Price = 6.5M, Name = "Product1" });
            Lines.Add(new CartLine() { ProductCode = "p2", Price = 12M, Name = "Product2" });


            var result = Lines
                   .GroupBy(l => l.ProductCode)
                   .SelectMany(cl => cl.Select(
                       csLine => new CartSummaryLine
                       {
                           Name = csLine.Name,
                           Quantity = cl.Count().ToString(),
                           TotalPrice = cl.Sum(c => c.Price).ToString(),
                       }));

            foreach (var l in result)
            {
                Console.WriteLine("Name:" + l.Name + "\tQuantity: " + l.Quantity + "\tPrice: " + l.TotalPrice);
            }
            Console.ReadLine();
        }
    }

    public class CartLine
    {
        public CartLine() { }

        public string ProductCode { get; set; }
        public decimal Price { get; set; }
        public string Name { get; set; }
    }

    public class CartSummaryLine
    {
        public CartSummaryLine() { }

        public string Name { get; set; }
        public string Quantity { get; set; }
        public string TotalPrice { get; set; }

    }