<?php
declare(strict_types=1);

$loans = [["id"=>21,"item"=>"Rake","quantity"=>2],["id"=>22,"item"=>"Saw","quantity"=>1]];
$total = 0;
foreach ($loans as $loan) {
    $total += $loan["quantity"];
    echo $loan["id"], ": ", $loan["item"], "\n";
}
echo "Units: ", $total, "\n";