$array1 =array("subj1"=>"10","subj2"=>"20","subj3"=>"30","subj4"=>"40","subj5"=>"36","subj6"=>"85");
print_r($array1);
Array
(
    [subj1] => 10
    [subj2] => 20
    [subj3] => 30
    [subj4] => 40
    [subj5] => 36
    [subj6] => 85
)
$array2=array("subj1"=>"110","subj2"=>"130");
print_r($array2);
Array
(
    [subj1] => 110
    [subj2] => 130
)

Array
(
    [subj1] => 110
    [subj2] => 130
    [subj3] => 30
    [subj4] => 40
    [subj5] => 36
    [subj6] => 85
)