<?php
error_reporting (-1);

$creditBalance = 40000;
$percent = 1.03;
$servicePayment = 1000;
$monthlyPayment = 5000;
$paymentTotal = 0;

for ($month = 1; $month <= 20; $month ++) {
	if ($creditBalance > $monthlyPayment) {
	$creditBalance = ($creditBalance * $percent) + $servicePayment - $monthlyPayment;
	}else{
		$monthlyPayment = $creditBalance;
		$creditBalance = 0;
	}
	$paymentTotal = $paymentTotal + $monthlyPayment;
	echo "{$month} месяц спустя: долг = {$creditBalance} руб, выплачено всего {$paymentTotal} руб. \n";
	
if ($creditBalance == 0){
	echo "Кредит выплачен..";
	break;
	
	}	
}