How do I make method that return true, if the book is free

How can i make this Method-  isFree () - returns true if the book is free

public class AudioBook extends Book {

	private String readerName;
	LocalTime recordDuration;
	private int priceForDownload; 
	
	
	public AudioBook(String bookName, String bookAuthor, LiteratureGenre bookGenre, Locale bookLanguage, LocalDate bookDateOfMade,String readerName, LocalTime recordDuration, int priceForDownload) {
		super(bookName,bookAuthor,bookGenre, bookLanguage,bookDateOfMade);
		this.readerName = readerName;
		this.recordDuration = recordDuration;
		this.priceForDownload = priceForDownload;
	}