Since Peter reads three times as fast as Kristin, Kristin will take 18*3 = <<18*3=54>>54 hours to read one book.

Kristin reads half of her books, a total of 20/2 = <<20/2=10>>10 books.

The time Kristin will take to read half of her books is 10*54 = <<10*54=540>>540

# Answer

540
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<|im_start|>user
Peter and Kristin are to read 20 fantasy novels each in a week. Peter can read three times as fast as Kristin. If Peter reads one book in 18 hours, how long will Kristin read half of her books?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
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user
540
Peter and Kristin are to read 20 fantasy novels each in a week. Peter can read three times as fast as Kristin. If Peter reads one book in 18 hours, how long will Kristin read half of her books?
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