using System;

public class Program : operaciones

{

    public static void Main()

    {

        a = 7;

        b = 8;

        Console.Write(sumar());

    }

}

public class operaciones{

    public static int a {get; set; }

    public static int b {get; set; }

    public static int sumar(){

        return a+b;

    }

    public static int restar(){

        return a-b;

    }

}

​