using System;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static List<Dictionary<string, decimal>> ListOfTimings = new List<Dictionary<string, decimal>> {

        new Dictionary<string, decimal>{

            {"a", 1},

            {"b", 2},

            {"c", 3}

        },

        new Dictionary<string, decimal>{

            {"a", 4},

            {"b", 5},

            {"c", 6}

        },

            new Dictionary<string, decimal>{

            {"a", 7},

            {"b", 8},

            {"c", 9}

        }

    };

    public static void Main()

    {

        var result2 = (from timings in ListOfTimings

                from timing in timings

                group timing by timing.Key into g

                select g)

                .ToDictionary(x => x.Key, x => x.Sum(y => y.Value));

        Console.WriteLine(string.Join(",", result2.Keys));

        Console.WriteLine(string.Join(",", result2.Values));

    }

}