some arrays playground

<?php
$twoDimensional = []; // [5][5]

// fill [5][5] with rand(1,100)
for ($i = 0; $i < 5; $i++) {
    for ($j = 0; $j < 5; $j++) {
        $twoDimensional[$i][$j] = rand(1,100);
    }
}


$normal = []; //[25]

// fill up to 25 elements between 30 and 70 in $normal
foreach ($twoDimensional as $firstDimension) {
    foreach ($firstDimension as $value) {
        if ($value >= 30 && $value <= 70 && count($normal) <= 25) {
            $normal[] = $value;
        }
    }
}

var_dump(array_sum($normal)); // the sum of all elements

sort($normal, SORT_DESC);

var_dump($normal); // let's see what in the array

/**
 *
 array (size=15)
    0 => int 31
    1 => int 32
    2 => int 34
    3 => int 37
    4 => int 40
    5 => int 41
    6 => int 47
    7 => int 59
    8 => int 59
    9 => int 60
    10 => int 60
    11 => int 61
    12 => int 62
    13 => int 64
    14 => int 65
 */