Question

{3x+y=3
{-x+2y=-8

Quanto é?

Answer 1

3x + y = 3
y = 3 - 3x

-x + 2y = -8
-x + 2 (3 - 3x) = -8
-x + 6 - 6x = -8
-x - 6x = -8 - 6
-7x = -14
x = 14/7
x = 2

3.x + y = 3
3.2+ y = 3
6 + y = 3
y = 3 - 6
y = -3

Answer 2

Vamos lá :

{3x + y = 3

{- x + 2y = - 8 .( 3)

{3x + y = 3

{ - 3x + 6y = - 24

______________+

y + 6y = 3 - 24

7y = - 21

y = - 21/7 = - 3

x = (3 - y)/3

x = (3 - (- 3))/3

x = (3 + 3)/3

x = 6/3 = 2

Espero ter ajudado !!!!