<?php

function rateBank(float $percents, int $servicePay = 0, int $additionalPay = 0) : array
{
    $total = 0;
    $creditBalance = 39999 + $additionalPay;
    $month = 0;
    while ($creditBalance > 0)
    {
        $month++;
        $creditBalance = $creditBalance * $percents + $servicePay;
        if($creditBalance < 5000)
        {
            $total += $creditBalance;
            break;
        }
        else
        {
            $total += 5000;
            $creditBalance -= 5000;
        }
    }
    return [ceil($total), $month];
}
print_r(rateBank(1.04, 500));
print_r(rateBank(1.03, 1000));
print_r(rateBank(1.02, 0, 7777));