<?php

function calc($sum, $pct, $comm) {
	$paid = 0;
	$payment = 5000;
	while ($sum > 0) {
		$sum  = ($sum * $pct) + $comm;
		$paid += $payment;
		$sum  -= $payment;
	}
	return $paid + $sum;
}

$iphone = 39999;

$homo = calc($iphone, 1.04, 500);
$soft = calc($iphone, 1.03, 1000);
$straw = calc($iphone+7777, 1.02, 0);

echo "$homo - $soft - $straw\r\n";