Answer:
Division Property of Equality
Explanation:
from the second from last step, we have
2x = -36
if we divide both sides of the equation equally by 2, we get
(2x ) / 2 = (-36) / 2
x = -18 ..., which is exactly the last step that is given in the question
hence in order to get to the last step, we divide both sides of the equality by 2 (a non-zero number).
AKA "Division Property of Equality"