soal_pertama

<?php

interface Hitung {
	public function calculate();
}

class Jumlah implements Hitung
{
	private $a;
	private $b;

	public function __construct($a, $b) {
		$this->a = $a;
		$this->b = $b;
	}
	public function calculate() {
		return $this->a + $this->b;
	}
}

class Kali implements Hitung
{
	private $a;
	private $b;

	public function __construct($a, $b) {
		$this->a = $a;
		$this->b = $b;
	}

	public function calculate() {
		return $this->a * $this->b;
	}
}

class Kurang implements Hitung
{
	private $a;
	private $b;

	public function __construct($a, $b) {
		$this->a = $a;
		$this->b = $b;
	}

	public function calculate() {
		return $this->a - $this->b;
	}
}

$jumlah = new Jumlah(20, 10);
$kali = new Kali(20, 10);
$kurang = new Kurang(20, 10);

echo $jumlah->calculate();
echo PHP_EOL;
echo $kali->calculate();
echo PHP_EOL;
echo $kurang->calculate();
echo PHP_EOL;