Alexa and rose read books that have the same number of pages. alexa’s book divided into 8 equal chapters. roses book is divided into 6 equal chapters. each girl has read 3 chapters of her book. write a fraction to describe what part of the book each girl read. then tell who read more pages. explain

Let's list out what we already know:
Alexa's book is into 8 chapters
Rose's book is into 6 chapters
So since they are out of how many chapters, they number of chapters their books are split into will be the denominator of each fraction. Each girl has already read 3 chapters, so they'll have 3 as their numerator.
Alexa: 3/8
Rose:3/6
We can see that Rose is already at half of the book while Alexa's half would be 4/8, and she isn't there yet. So Rose read more of her book.