GetBooksReleasedBefore

        public static string GetBooksReleasedBefore(BookShopContext context, string date) //06.
        {
            DateTime inputDate = DateTime.ParseExact(date, "dd-MM-yyyy", null);
            var result = context.Books
                .Where(b => b.ReleaseDate < inputDate)
                .OrderByDescending(b => b.ReleaseDate)
                .Select(b => $"{b.Title} - {b.EditionType} - ${b.Price}:f2"); //added :f2
            return string.Join(Environment.NewLine, result);
        }