Система рівнянь 7x+6y=29
3x-5y=20

{7x + 6y = 29   {7x + 6y = 29      {7x + 6(-4 + 3\5x) =29

                      ;                         ;                                        ;

{ 3x - 5y = 20   {-5y = 20 - 3x      {y =- 4 + 3\5x

{ 7x - 24 + 18\5x = 29      { 7x + 3.6x = 29 + 24      {10.6x = 53

                                      ;                                     ;                          ;

{ y = -4 + 0.6x                  { y = -4 + 0.6x                 { y = -4 + 0.6x

{x = 5                { x = 5

                     ;

{ y = -4 + 3      { y = -1

ответ : ( 5;-1)