Monica has read 6/8 of a book. she has read the same number of pages each day for 6 days. what fraction of the book does monica read each day?

The number of pages that Monica reads from a book = 6/8
The total number of days taken by Monica to read 6/8 pages = 6
It is also given in the question that Monica reads the same number of pages each day. this makes the problem simple enough to deduce.
Number of pages that Monica reads each day = (6/8)/6
                                                                           = 6/(8 * 6)
                                                                           = 1/8
So Monica reads 1/8 fraction of the book each day. I hope the procedure is easy enough for you to understand.