<?php

error_reporting(-1);

function countTotal($sum, $percent, $comm, $also, $pay) {
	$total = 0;
	$sum += $also;
	for (; $sum > 0;) {
		$sum = $sum * $percent + $comm;
		if ($sum > $pay) {
		    $total += $pay;
		    $sum -= $pay;
		} else {
			$total += $sum;
			$sum = 0;
		}
	}
	return $total;
}

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

echo "homoCreditTotal: {$homoCreditTotal} руб.\n";
echo "softBankTotal: {$softBankTotal} руб.\n";
echo "strawberryBankTotal: {$strawberryBankTotal} руб.\n";