using System;

using System.Linq;

using System.Text;

using System.Collections.Generic;

using System.Security.Cryptography;

​

public class Card

{

    public string Code { get; set; }

    public int Amount { get; set; }

}

​

public class Program

{

    public static void Main()

    {

        List<Card> cards = new List<Card>

        {

            new Card { Code = "abc", Amount = 5 },

            new Card { Code = "abc", Amount = 5 },

            new Card { Code = "abc", Amount = 5 },

            new Card { Code = "zxc", Amount = 10 },

            new Card { Code = "zxc", Amount = 10 },

            new Card { Code = "zxc", Amount = 10 },

        };

        cards.GroupBy(x => x.Code, y => y.Amount, (k, g) => new { k, s = g.Sum(x => x) }).ToList().Dump();

        cards.GroupBy(x => new { x.Code, x.Amount }).Select(x => new {x.Key.Code, x.Key.Amount, Sum = x.Sum(y => y.Amount)} ).ToList().Dump();

    }

}