3х-х (в кводрате)+2х(в кводрате)=х                         2х(в кводрате)+3х=х-х(в кводрате)
---------------------           -----------------                              ----------------           ---------------
             2                          2                                            3-х                     3-х

№3
5х-7=4х-3                                                       №4         2х+3=3х+2
------  ------                                                                       -------  -------
х-3      х                                                                          х+2    х

№5
4   - 5 = 1
----  -----  -----                                        №6        5y+13  -  4-6y  =  3
x+3  3-x x-3                                                     ----------      ------   
                                                                        5y+4        3y-1