Answer:
(4,3) (4,5)
Step-by-step explanation:
First add 5 to 16, so -3x=21
then divide by -3, so the answer is
x= -7
The vertex form:

(h,k) - the coordinates of the vertex

The coordinates of the vertex are
(-4,13).
Answer:
x=2
Step-by-step explanation:
Solution is attached
You can plug 2 back into the equation to verify :)