how do you solve this using substitution of system equations here's the problem -4=x-2y and -x+2=-y

Second equation:

-x+2=-y Multiply with(-1)
x-2=y

y=x-2

If y=x-2 then 2y=2*(x-2)=2x-4

In first equation:

-4=x-2y
-4=x-(2x-4)
-4=x-2x+4
-4+(-4)=-x
-8=-x
-x=-8 Multiply with(-1)

x=8

In second equation y=x-2
y=8-2
y=6

x=8 y=6

Proof:
First equation:
-4=x-2y
-4=8-2*6
-4=8-12
-4=-4

Second equation:
-x+2=-y
-8+2=-6= -y