Since the scale factor is 0.5, it means that you have to divide in half each side.
x= 7/2= 3.5
y= 12/2= 6
z= 6/2= 3.25
The equation is not setup properly, possibly it is your teacher's fault.
From external research, I would say the answer is x = -12.
The correct answer is both
Infinitely many, hope that helped
