static void Main(string[] args) { Book firstBook = new Book("UNIBIT", "Ivan", "Edu", 23.00m); Book secondBook = new Book("UNI", "Mariq", "Moodle", 28.00m); BookInfo info = new BookInfo(); info.ShowBookInfo(firstBook); info.ShowBookInfo(secondBook); firstBook.Price = 0.00m; secondBook.Price -= -11.00m; info.ShowBookInfo(firstBook); info.ShowBookInfo(secondBook); }