Lilly has read seven-eighths of her book and is on page 147. How many pages does lilly have left to read?

21

Step-by-step explanation:

Since Lilly has read 7/8 of her book (aka 147 pages), divide 147 by 7 and you get 21.

This means 1/8=21

Since she has read 7/8 of the book, and the full book is 8/8, 8/8-7/8 = 1/8

Meaning she has 1/8 of the book left to read.

As said before, 1/8 = 21

Thus, she has 21 pages left to read.