<?php

function getBalanceFuture($percent, $commission) {
    $creditBalance = 39999;
    $payout = 5000;

    for ($month = 1; $creditBalance > 0; $month++) {
        $creditBalance = ($creditBalance * $percent) + $commission;
        if ($creditBalance > $payout) {
            $paymentTotal += $payout;
            $creditBalance -= $payout;
        } else {
            $paymentTotal += $creditBalance;
            $creditBalance = 0;
        }
        
    }
    return $paymentTotal;
    return $month;
}

$HomoCreditTotal = getBalanceFuture(1.04, 500);
$SoftBankTotal = getBalanceFuture(1.03, 1000);
$StrawBerryBankTotal= getBalanceFuture(1.02, 0) +  7777;

echo "homo Credit: {$HomoCreditTotal} руб. Оплачено всего: {$paymentTotal} за {$month} месяцев<br>";
echo "Soft Bank: {$SoftBankTotal} руб. Оплачено всего: {$paymentTotal} за {$month} месяцев<br>";
echo "Straw Berry: {$StrawBerryBankTotal} руб. Оплачено всего: {$paymentTotal} за {$month} месяцев<br>";