Respuesta :

Answer:

x= -30

Step-by-step explanation:

y=x+12    y=-18

Substitute:   -18=x+12

Solve:           x= -30

Answer:

x=-30 (correct me if I am wrong)

Step-by-step explanation:

y=x+12

-18=x+12

-18-12=x

-18+-12=x

-18+-12=-30

x=-30