Well, to start, name the arrays differently
<?php
$arrayOne = array(1,2,3,4,5);
$arrayTwo = array("a","b","c","d","e");
/*
then loop through them,
adding them to a string
*/
$string="";
for($i=0;$i<count($arrayOne);$i++) {
$string .= $arrayOne[$i].$arrayTwo[$i].", ";
}
/* remove the last comma and space */
$string = substr(rtrim($string),0,-1);
echo $string;
?>