Kak to solve a task - when Petya studied in the second grade, speed its reading was 45slov/the min. reading speed in the fourth class peti-135slov/the fourth-grader Petya, min. in how many hours, could read the book which in the second class he read during 4 h?

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135:45=3 (rubles) - in the speed of reading 2) 4:3=1 1/3 (h) 1/3 Parts =60/3 1 1/3 Parts =1 of the Part of 20 min. increased min. =20 min. so many. Answer: the fourth-grader Petya could read the same book in 1 1/3 hour or in 1 hour 20 minutes.
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Answer add