9 -12 .

  →    →  - 6-3 8-3   →  9 -12 .  

 

1                                                                              1
2                                                            1( )
3          ( )       1
4                                                                            4
5          24 7798-70                                        2
6          16 5915-70                                       16
7          24 5915-70                                       4
8          16.019 11371-78                              4