Answer:
C
Step-by-step explanation:
x + 11 = 24
x = 13
If x=3
(1/3)y2+12=15
(1/3)y2=15-12
(1/3)y2=3
y2=3*3
y2=9
y=3
The vertex form:

(h,k) - the coordinates of the vertex

The coordinates of the vertex are
(-4,13).
I think the answer is 42.
12 slices in total (6 slices per pizza)