<?php $var1 = '3006'; $var2 = '40416'; $var3 = '966'; $var4 = '30'; $str = '$var1 + ($var2-$var3) / $var4.<br>'; eval ("echo $var1 + ($var2-$var3) / $var4;"); ?>
$expression = "3006 + (40416-966) / 30"; eval('$result = '.$expression.';');