<?php

error_reporting(-1);

$creditBalance = 40000;
$monthlyPayment = 5000;
$rate = 1.03;
$servicePayment = 1000;
$payedTotal= 0;

for ($month = 1; $creditBalance > 0; $month++) {
	$creditBalance = ($creditBalance * $rate) + $servicePayment - $monthlyPayment;
	$payedTotal += $monthlyPayment;
	if ($creditBalance < 0){
		$payedTotal += $creditBalance;
		$creditBalance = 0;
	}
	echo "Шёл $month месяц. Долг школьника - $creditBalance рублей, всего выплатил - $payedTotal рублей.\n";
}

?>