Verified answer

[tex]\displaystyle\bf\\\left \{ {{x + y = 28} \atop {x - y = 14 }} \right. \\ \displaystyle\bf\\\left \{ {{14 +y + y = 28} \atop {x = 1 4+ y {}^{} }} \right. \\ \\ 14 + 2y = 28 \\ 2y = 28 - 14 \\ 2y = 14 \\ = 14 \div 2 \\ y = 7 \\ \\ x = 14 + 7 \\ x = 21[/tex]

Ответ: ( 21 ; 7 )

Ответ:

(21; 7)

Пошаговое объяснение:

{х + у = 28

{х - у = 14

{у = 28 - х

{х - у = 14

1)

х - у = 14

х - (28 - х) = 14

х - 28 + х = 14

2х = 14 + 28

2х = 42

х = 42 : 2

х = 21

2)

у = 28 - х

у = 28 - 21

у = 7