Does this Dell run Windows? (a search on the web tells me it does)
If so I would guess folder MyPictures would be a good place to start.
One web site says they are saved in a folder called "Camera Roll" which I think is in MyPictures.
If you are running Windows 10 seems there is an app called Microsoft Photos (or maybe just Photos) used for viewing all your photos and videos.
Sorry cant be more help but don't have a Windows tablet to hand.