<?php 
$dogru = "12"; 
$hepsi = "24"; 
$bos = "2"; 
$yanlis = "12";
$gotur = $yanlis / 3;
$dogru = $dogru - $gotur;
$yuzde = $dogru * 100 / $hepsi ; 
$enson = "%"; 
echo  "$enson $yuzde";
?>