Sophia finished 23 of a book. She calculated that she finished 90 more pages than she has yet to read. How long is her book?	Pick: A) 180 B) 200 C) 250 D) 270 E) 300
Let x be the total number of pages in the book, then she finished 23⋅x pages.   Then she has x−23⋅x=13⋅x pages left.   23⋅x−13⋅x=90   13⋅x=90   x=270.   So answer is 270.
<result>D</result>
Sophia finished 23 of a book. She calculated that she finished 90 more pages than she has yet to read. How long is her book?