<?php
error_reporting(-1);
 
function getBalanceInFuture($credit,$percent,$comission,$payment,$payout,$total) {
	for ($i=$credit;$i>=0;$i-=$payout) {
    if ($payment==7777) {
    $total= $total + $credit * $percent + $comission + $payment;
    $credit = $credit + $credit * $percent + $comission + $payment;
    
    $payment++;}
    else { 
    $total= $total + $credit * $percent + $comission;
    $credit = $credit + $credit * $percent + $comission;
    
    }
	}
	return $total;
}
$homoTotal= getBalanceInFuture(39999,0.04,500,0,5000,39999);
$softTotal= getBalanceInFuture(39999,0.03,1000,0,5000,39999);
$strawberryTotal= getBalanceInFuture(39999,0.02,0,7777,5000,39999);
echo "Школьник будет должен банку {$homoTotal}руб.\n";
echo "Школьник будет должен банку {$softTotal}руб.\n";
echo "Школьник будет должен банку {$strawberryTotal}руб.\n";