12. x + y = 4
And the next question is
13. -7 x = y
Pls answer ASAP and explain why!! Thank you!!


Answer :

Answer:

[tex]x = - \frac{2}{3} \: \: \: y = \frac{14}{3} [/tex]

Step-by-step explanation:

Since we know -7x=y we use the substitution method and plug it in the top equation.

[tex]x + - 7x = 4[/tex]

[tex] - 6x = 4[/tex]

[tex]x = - \frac{4}{6} [/tex]

or x=-2/3

Then plug it back in the the bottom equation

[tex] - 7( \frac { - 2}{3} ) = y[/tex]

y=14/3