Sophia finished 2 3 of a book she calculated that 90 more pages than has yet to read How long is her book?

To find the total number of pages in Sophia's book, you need to divide the number of pages she has yet to read (90) by the fraction of the book she has finished (2/3).

Let P be the number of pages in the book.

- So far she has read: (2/3) of P pages.

=> 2P / 3 pages.

- She has 90 more pages to read:

=> (2P/ 3) + 90 = P

=> 2P + 270 = 3P

=> 270 = P - 2P

=> 270 = -P

=> P = 270 pages

Therefore, the total number of pages in the book is 270.