<human>:  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?
<bot>: How many hours will Kristin take to read one book? ** Since Peter reads three times as fast as Kristin, Kristin will take 18*3 = <<18*3=54>>54 hours to read one book.
How many books does Kristin read? ** Kristin reads half of her books, a total of 20/2 = <<20/2=10>>10 books.
How many hours will Kristin take to read half of her books? ** The time Kristin will take to read half of her books is 10*54 = <<10*54=540>>540
#### 540