Kiara’s comic books are cheaper, costing $0.70 per book.
First, find the unit rate for Benny’s books. $6/8 books, so you need to divide $6 by 8 to get how much one book costs. In this case, you get $0.75, so the unit rate for Benny’s books is $0.75/book.
Now, find Kiara’s unit rate. Her books are $7/10 books, so divide $7 by 10 to get $0.70. So, the unit rate for Kiara’s books is $0.70/book.