Answer: Keiko paid less per book and thus got the better deal.
Step-by-step explanation: Keiko bought 5 books for $6.25, so the price per book is $6.25 divided by 5 books, which equals $1.25 per book.
Bryan bought 4 books for $5.80, so the price per book is $5.80 divided by 4 books, which equals $1.45 per book.
Therefore, Keiko got the better deal because she paid $1.25 per book, while Bryan paid $1.45 per book. Keiko paid less money for each book compared to Bryan.