<?php
function calculate($credit, $pay, $commission, $percent, $bonus)
{
    $tPay = 0;
    $credit = $credit + $bonus;
    for ($month = 1; $credit > 0; $month++) {
        $debt = round($credit * $percent + $commission);
        if ($debt < $pay) {
            $pay = $debt;
        }
        $credit = $debt - $pay;
        $tPay += $pay;
    }
    return $tPay;
}
 
$credit = 39999;
$pay = 5000;
$HomoCredit = calculate($credit, $pay, 500, 1.04, 0);
$SoftBank = calculate($credit, $pay, 1000, 1.03, 0);
$StrawberryBank = calculate($credit, $pay, 0, 1.02, 7777);
echo "\nHomoCredit: $HomoCredit руб.";
echo "\nSoftBank: $SoftBank руб.";
echo "\nStrawberryBank: $StrawberryBank руб.";

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