Ответы и объяснения

2013-04-05T21:02:39+04:00

210      420

----- =  ------         =    420с= 210 * 6

  с          6                   420 с= 1260

                                    с =  1260 / 420

                                     с =3

 вот так))

2013-04-05T21:11:21+04:00