I purchased the 30 pack box, not the 3 pack. However, reading the listing details and looking at the product picture, this 3 pack would get you 3 boxes with 10 in each. So 30 bags total. The 30 count value pack box gets the most bang for your buck, at least at the moment's pricing. Hope that helps.
I have to imagine that they would work well. We use the Arm & Hammer small bags for our dog as well because of the great job it does containing the smell. But I haven't used these specifically for the dog.