Respuesta :

Answer:

C.  2x - 3(-3x - 4) = -21.

Step-by-step explanation:

y + 3x = -4

2x - 3y = -21

From the first equation y = -3x - 4.

Substituting this for y in the second equation, we have:

2x - 3(-3x - 4) = -21.