using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

​

public class Test{

    public decimal x {get;set;}

}

public class Program

{

    public static void Main()

    {

        var testlist = new List<Test>();

        testlist.Add(new Test(){x= 1});

        testlist.Add(new Test(){x= 1});

        testlist.Add(new Test(){x= 1});

        testlist.Add(new Test(){x= 1});

        decimal c = testlist.Sum(x=> x.x);

        Console.WriteLine(c);

    }

}