using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var items = new List<Item>

        {

            new Item

            {

                TransactionValue = 10,

                TransactionType = "Income"

            },

            new Item

            {

                TransactionValue = 10,

                TransactionType = "Income"

            },

            new Item

            {

                TransactionValue = -5,

                TransactionType = "Outgoing"

            },

            new Item

            {

                TransactionValue = -20,

                TransactionType = "Outgoing"

            }

        };

​

            Totals result = new Totals

                              {

                                  TotalIncoming = items.Where(x => x.TransactionType == "Income").Sum(x => x.TransactionValue),

                                  TotalOutgoing = items.Where(x => x.TransactionType == "Outgoing").Sum(x => x.TransactionValue)

                              };

​

            List<ItemTotals> query = items.GroupBy(x => x.TransactionType)

                                          .Select(x => new ItemTotals

                                          {

                                              ItemType = x.Key,

                                              Total = x.Sum(z => z.TransactionValue)

                                          }).ToList();

​

            Console.WriteLine("TotalIncoming : {0}", result.TotalIncoming);

            Console.WriteLine("TotalOutgoing : {0}", result.TotalOutgoing);

            Console.WriteLine();

​

            foreach (var item in query)

            {

                Console.WriteLine("ItemType : {0}", item.ItemType);

                Console.WriteLine("Total : {0}", item.Total);

            }

    }

}

​

class Item

    {

        public decimal TransactionValue { get; set; }

        public string TransactionType { get; set; }

    }

​

class Totals

    {

        public decimal TotalIncoming { get; set; }

        public decimal TotalOutgoing { get; set; }

    }

​

    class ItemTotals

    {

        public string ItemType { get; set; }

        public decimal Total { get; set; }

    }