First divide 32 by 3, ignoring the remainder, to find how many chapters in the book are divisible by 3: 31 / 3 = 10.33..., which means 10 chapters are divisible by 3
Then subtract that number from the total number of chapters to find how many chapters she reads: 31 chapters - 10 chapters = <<31-10=21>>21 chapters
Then multiply the number chapters by the time to read each chapter to find the total time she spends reading: 21 chapters * 20 minutes/chapter = <<21*20=420>>420 minutes
Then divide that time by the number of minutes per movie to find the total time spent reading in hours: 420 minutes / 60 minutes/hour = <<420/60=7>>7 hours
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