If there are 88 pages in the album, and only half of them are full, we can divide 88 by 2 to get the amount of pages that are full with cards.
88/2 = 44
If each page can fit four cards, and 44 pages are full, we can multiply 44 by 4 to get how many cards are in the album.
44 x 4 = 176
Therefore, there are 176 cards in the album.
Hopefully this helps! :)