<?php

error_reporting(-1);

function repayment($creditBalance, $percent, $monthlyPayment, $servicePayment, $openingAccount = 0) {

    $paymentTotal = 0; /* Сколько всего отдал банку анон */
    $creditBalance += $openingAccount; /* В случае оплаты за открытие счета */

    while($creditBalance > 0) {
    	$creditBalance = ($creditBalance * $percent) + $servicePayment;
    	if ($creditBalance <= $monthlyPayment) {
    		$monthlyPayment = $creditBalance;
    	}
    	$creditBalance = $creditBalance - $monthlyPayment;
    	$paymentTotal = $paymentTotal + $monthlyPayment;
    }
    return $paymentTotal;
}

$homoCreditTotal = repayment(39999, 1.04, 5000, 500);
$softBankTotal =  repayment(39999, 1.03, 5000, 1000);
$strawberryBankTotal = repayment(39999, 1.02, 5000, 0, 7777);

echo "homoCredit {$homoCreditTotal} руб.\n";
echo "softBank {$softBankTotal} руб.\n";
echo "strawberryBank {$strawberryBankTotal} руб.\n";