C++ I need to enhance the code

that's the project and I have this code that I need to improve

here is the score I get

I need to use the appropriate class relationship and the program logic needs to be good.

Question 1 16 pts If you are asked to write three classes : class Person, BookAuthor, and Book. The class Person involves with a person's identity. The class BookAuthor involves with a collection of books or book titles. The class Book involves number of books in stock , book title, and price. Design the three classes . The classes must use appropriate relationships. Each class must have two constructors, one is the default and the other is an overloaded constructor. Each class has at least two private data members. Try not to use too many member functions due to the time you have. See the grading criteria what you will be assessed on. You are allowed to use one file for the classes, implementations, and the main(). If using separate files, you will earn 2 extra points. Below is the main() which will give you a good clue on developing your classes: int main(). { Book Cplusbk("Tony Gaddis", "C++ Early Object", 2013, 57.8, 500); // (Author's name, year published, price, and number of books in stock) Cplusbk.Display(); // displays the Author's name, title, year published, price, and number of books in stock. Book bk1(50.0), bk2(80.0), bk3; // The following line with its question is worth 2 points if your answer is correct. bk3 = bk1 + bk2; // As a result, bk3 contains 130.0 as its price. //Question: What do you need to declare in the class and define to #include using namespace std; class Person { char personName; Person { char personName = 'Cesa'; cout