如何找到多个数组的最大值[关闭]

eg I have several arrays like this:

$data1 = array(80, 'P3');
$data2 = array(55, 'P3');
$data3 = array(90, 'P3');

how to find the greatest value of some of the array? help me please, thanks :)

$x = array_merge($data1, $data2, $data3);
sort($x);
$highest = array_pop($x);