Создать базовый класс «Транспортное средство» и производные классы «Автомобиль», «Велосипед», «Повозка»

<?php
class Carrier {
    public $unit;
    public $time = 'мин.';
    public $price = 'руб.';
    
    public function __construct($u){
        $this->unit = $u;
    }
    static function getInstance($unit,$class){
         return new $class($unit);
    }   
}
 
class Aircraft extends Carrier {
    private $time_for_unit = 60;
    private $price_for_unit =120;
    
    public function getTime(){
        return ($this->unit * $this->time_for_unit).$this->time;
    }
    
    public function getPrice(){
        return ($this->unit * $this->price_for_unit).$this->price;
    }
}
 
class Train extends Carrier {
    private $time_for_unit = 160;
    private $price_for_unit = 100;
    
    public function getTime(){
        return ($this->unit * $this->time_for_unit).$this->time;
    }
    
    public function getPrice(){
        return ($this->unit * $this->price_for_unit).$this->price;
    }
}
 
class Car extends Carrier {
    private $time_for_unit = 140;
    private $price_for_unit = 100;
    
    public function getTime(){
        return ($this->unit * $this->time_for_unit).$this->time;
    }
    
    public function getPrice(){
        return ($this->unit * $this->price_for_unit).$this->price;
    }
}
 
$arrierAircraft = Carrier::getInstance('10', 'Aircraft');
$res_time = $arrierAircraft->getTime();
$res_price = $arrierAircraft->getPrice();
echo '<div>' . $res_time . '</div>';
echo '<div>' . $res_price . '</div>';
?>