<?php
 
error_reporting(-1);
 
$creditBalance  = 4000;
$percent        = 1.03;
$servicePayment = 1000;
$monthlyPayment = 5000;
$paymentTotal   = 0;
 
for ($month = 1; $month <= 20; $month++) {
 
    $creditBalance = ($creditBalance * $percent) + $servicePayment - $monthlyPayment;
    $paymentTotal  = $paymentTotal + $monthlyPayment;
    echo "{$month} месяц спустя: долг = {$creditBalance} руб, выплачено всего {$paymentTotal} руб. \n";
 
    if ($creditBalance < 5000) {
        echo "Осталось выплатить всего {$creditBalance} и кредит погашен.\n";
        break;
    }
}

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