<?php
error_reporting(-1);
function totalPay($creditSum, $monthPay, $monthPercent, $tax){
    for ($i = 0; $i <= 20; $i++){
    	$totalPayBank = $creditSum * $monthPercent + $tax - $monthPay;
    	$total = $total + $monthPay;
    }
    return $total;
}

$creditSum = 39999;
$monthPay = 5000;
$homoCreditTotal = totalPay(39999, 5000, 1.04, 500);
$softBankTotal = totalPay(39999, 5000, 1.03, 1000);
$strawberryBank = totalPay(39999, 5000, 1.02, 7777);

echo "{$homoCreditTotal}\n";
echo "{$softBankTotal}\n";