libs; $cartridgesInStorage = 0; foreach ($libs as $lib) { $cartridgesInStorage += $lib->fullSlots; } $emptyStorageSlots = $counts->slot_count - $counts->unassigned_slot_count - $cartridgesInStorage; $fullStorageSlots = $counts->slot_count - $counts->unassigned_slot_count - $emptyStorageSlots; ?>