<human>:  Jo reads at a steady pace. Her current book has 210 pages. Now, she is at page 90. An hour ago, she was at page 60. For how many hours will she be reading the book?
<bot>: How many pages does Jo read in an hour? ** She reads 90-60=<<90-60=30>>30 pages in an hour.
How many more pages does Jo need to read? ** She needs to read 210-90=<<210-90=120>>120 more pages.
How long will it take her to finish the book? ** For an additional 120 pages, she will need 120/30=<<120/30=4>>4 hours.
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