Untitled

<?php

$firstArray = [
    //j=0, j=1
    [  3, 2, 4], // $i = 0
    [  4, 6, 7]  // $i = 1
];

$secondArray = [
    [7, 8, 4],
    [2, 6, 9]
];

$total = [];

for($i = 0; $i < sizeof($firstArray); $i++){

    for($j = 0; $j < sizeof($firstArray[$i]); $j++){
        
        $total[$i][$j] = $firstArray[$i][$j] + $secondArray[$i][$j];

    }

}

for($i = 0; $i < count($total); $i++){


    for($j = 0; $j < count($total[$i]); $j++){

        echo $total[$i][$j];

        if($j != sizeof($total[$i]) - 1){
           
            echo ", ";

        }
    }

    echo PHP_EOL;

}