Calculate costumize array

fiddle_243637.php

<?php

function calculate($array_1, $array_2){
	$x = 0; $total = 0;
	
	foreach($array_1 as $element){
		$total += ($element - $array_2[$x]);
		$x++;
	}
	
	return ($total / count($array_1));
}

echo calculate(array(6, 3, 3, 4), array(8, 7, 6, 5));

?>