Inheritrance Balok

<?php

class PersegiPanjang {
    public $panjang;
    public $lebar;
    
    public function luas() {
        return $this->panjang * $this->lebar;
    }
}

class Balok extends PersegiPanjang {
    public $tinggi;
    
    public function volume() {
        return $this->panjang * $this->lebar * $this->tinggi;
    }
}

$balok = new Balok();

$balok->panjang = 10;
$balok->lebar = 5;
$balok->tinggi = 3;

echo "Persegi Panjang dan Balok\n";
echo "Panjang = $balok->panjang\n";
echo "Lebar = $balok->lebar\n";
echo "Tinggi = $balok->tinggi\n";

echo "Luas Persegi panjang = {$balok->luas()}\n";
echo "Volume Balok = {$balok->volume()} \n";