question: Mike's teacher, leaves as homework the reading of a 200-page book. The assignment is to be completed within 30 days. Mike plans to read 10 pages a day. How many days before the deadline will Mike finish his reading?
answer: Reading 10 pages per day, Mike finishes reading his book in 200 ÷ 10 = <<200/10=20>>20 days.
  Mike finishes reading his book 30 - 20 = <<30-20=10>>10 days before the deadline.
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