Question

12. x + y = 4

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

Answer 1

`x = - (2)/(3) \: \: \: y = (14)/(3)`

Explanation:

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

`x + - 7x = 4`

`- 6x = 4`

`x = - (4)/(6)`

or x=-2/3

Then plug it back in the the bottom equation

`- 7( \frac { - 2}{3} ) = y`

y=14/3