inheritance-oop

<?php

class employee{
    public $name;
    public $age;
    public $salary;

    function __construct($n, $a, $s){
        $this->name = $n;
        $this->age = $a;
        $this->salary = $s;
    }

    function info(){
        echo "<h3>Employee info</h3><br>";
        echo "Employee name : ".$this->name."<br>";
        echo "Employee age : ".$this->age."<br>";
        echo "Employee salary : ".$this->salary."<br>";
    }
}

class manager extends employee{
    public $ta = 1000;
    public $phone_bill = 300;
    public $total_salary;

    function info(){
        $this->total_salary = $this->salary + $this->ta + $this->phone_bill;
        echo "<h3>Manager info</h3><br>";
        echo "Manager name : ".$this->name."<br>";
        echo "Manager age : ".$this->age."<br>";
        echo "Manager salary : ".$this->total_salary."<br>";
    }

}

$e1 = new employee("Emran", 21, "5000");
$e1->info();

$e2 = new manager("Yousuf", 23, "10000");
$e2->info();

?>