gistfile1.txt

$a = array(
    0 => array(
        0=>10,
        1=>10,
        2=>10
    ),
    1 => array(
        0=>43,
        1=>78,
        2=>78,
    ),
    2 => array(
        0=>12,
        1=>532,
        2=>46,
    ),
);
$sum = array();
$i=0;
while($i < count($a)){
    $buffer = 0;
    $i++;
    $j=0;
    while($j < count($a[$j])){
        $buffer = $buffer + $a[$i][$j];
        $j++;
    }
    $sum = $buffer;
}
var_dump($sum);