Question

I'm so confused! okay! Rearrange into transformational form and state the vertex!

Y=-2X^2-12x+54
-1/2 Y =X^2 +6X-27
-1/2Y +27 = X^2+12X
-1/2Y+27 = X^2+12X+9-9
-1/2Y+27 = (X+3)^2 - 9
-1/2Y+36 = (X+3)^2

The vertex that I'm given for the answer is: (-3, 72)
Where did I go wrong? I'm getting -3 and -36 for my vertex.