class MyBook extends Book {

    protected $price;

    function __construct($title,$author,$price) {
        Book::__construct($title, $author);
        $this->price = $price;
    }
    
    function display() {
        echo "Title: {$this->title}";
        echo "Author: {$this->author}";
        echo "Price: {$this->price}";
    }
}