using System;

using System.Linq;

using System.Collections.Generic;

​

//https://stackoverflow.com/questions/67378957/c-sharp-splitting-a-liststring-value

public class Program

{

    public static void Main()

    {

        List<string> myList = new List<string>();

        myList.Add("1 120 12");

        myList.Add("1 130 22");

        myList.Add("2 110 21");

        myList.Add("2 100 18");

        var query = myList.Select(a => a.Split(' ').Select(int.Parse).ToArray())

            .GroupBy(

              index => index[0], 

              amount => new

                    {

                        First = amount[1],

                        Second = amount[2]

                    }, 

              (index, amount) => new

                    {

                        Index = index, 

                        SumFirst = amount.Sum(a => a.First), 

                        SumSecond = amount.Sum(a => a.Second) 

                    }

                    );

        foreach (var result in query)

        {

            Console.WriteLine(result.Index + " " + result.SumFirst + " " + result.SumSecond);

        }

    }

}

​

​