Hello today i arrive to this post in linkedin and try to find a solution, but i can't see clearly the best solution about it, i put a the problem below.

Please modify the value of $c so that the following script outputs HelloWorld (and it can only be modified once):

<?php
$a = 'Hello';
$b = 'World';
$c = '';
if ($a == $c) {
  echo $a;
}

if ($b == $c) {
  echo $b;
}