Respuesta :

mhanifa

Answer:

-7

Step-by-step explanation:

y−x=9 ⇒ y=x+9

10+2x=−2y

5+x= -y  ====== replacing y with x+9

5+x= -x-9

2x= -14

x= -7

09pqr4sT

Answer:

-7

Step-by-step explanation:

y - x = 9

10 + 2x = -2y

Solve for y in the first equation.

y = 9 + x

Put y as 9 + x in the second equation and solve for x.

10 + 2x = -2(9 + x)

10 + 2x = -18 - 2x

2x + 2x = -18 - 10

4x = -28

x = -28/4

x = -7