Решить систему уравнений методом алгебраического сложения

а) 3х - 2у = 64                          б)3х + 2у= -27

     3х + 7у = -8                            -5х + 2у=13

   3x - 2y = 64                                                                        

3x + 7y = -8

3x= 64 + 2y

(64 + 2y) + 7y = -8

64 + 9y = - 8

9y = -72

y = - 8

 б) 3x + 2y = -27

      - 5x + 2y = 13

         2y = -27 - 3x

         - 5x = 13 - ( - 27 - 3x)

          - 5x= 13 +27 + 3x 

           -5x = 40 + 3x

             - 8x = 40

                x = -5 

а) 3x - 2y = 64

     3x+7y=-8                                                                                                     3x-2y=64

                                                                                                                            3x+7y=-8

                                                                                                                             --------------

                                                                                                                                  -9y=72

                                                                                                                                     Y=-8

3x-2y=64

Y=-8

3x-2*(-8)=64

Y=-8

3x+16=64

Y=-8

3x=48

Y=-8

X=16

Y=-8