Решите системы

2х+у=12

3х-у=3 (сложение)

2х+3у=13

4х+5у=23 (подстановка)

810  2      810=2*3*3*3*3*5        252  2       252=2*2*3*3*7   
405  3                                      126  2 
135  3                                        63  3
 45  3                                         21  3
 15  3                                           7  7
  5  5                                            1
  1

1110  2         1110=2*3*5*37         11  11      11=11
  555  3                                         1
  185  5
    37  37
      1

1001  7          1001=7*143              1225  5            1225=5*5*7*7
 143  143                                        245  5
     1                                                49  7         
                                                         7  7
                                                         1 

21780  2        21780=2*2*3*3*5*121        45630  2     45630=2*3*3*3*5*169
10890  2                                              22815  3
  5445  3                                                7605  3
  1815  3                                                2535  3  
    605  5                                                 845  5
    121  121                                             169  169
       1                                                        1

810  2      810=2*3*3*3*3*5        252  2       252=2*2*3*3*7   
405  3                                      126  2 
135  3                                        63  3
 45  3                                         21  3
 15  3                                           7  7
  5  5                                            1
  1

1110  2         1110=2*3*5*37         11  11      11=11
  555  3                                         1
  185  5
    37  37
      1

1001  7          1001=7*143              1225  5            1225=5*5*7*7
 143  143                                        245  5
     1                                                49  7         
                                                         7  7
                                                         1 

21780  2        21780=2*2*3*3*5*121        45630  2     45630=2*3*3*3*5*169
10890  2                                              22815  3
  5445  3                                                7605  3
  1815  3                                                2535  3  
    605  5                                                 845  5
    121  121                                             169  169
       1                                                        1