2< 3x+1< 7 решите двойные неравенства в учебнике ответ (-1, 2) решите 10

7200
700 десятков это 7000                                                               7 десятков=70
20 десятков это 200                                                                 70 десятков =700
                                                                                               700десятков =7000
                                                                                               2 десятка =20
                                                                                              20 десятков =200
                                                                                            200 десятков=2000

7200
700 десятков это 7000                                                               7 десятков=70
20 десятков это 200                                                                 70 десятков =700
                                                                                               700десятков =7000
                                                                                               2 десятка =20
                                                                                              20 десятков =200
                                                                                            200 десятков=2000