03.GetBooksByPrice

public static string GetBooksByPrice(BookShopContext db)
        {
            var booksByPrice = db.Books
                .OrderByDescending(b => b.Price)
                .Where(b => b.Price > 40)
                .Select(b => $"{b.Title} - ${b.Price}")
                .ToList();

            var result = String.Join(Environment.NewLine, booksByPrice);
            return result;
        }