ANSWER
It was given that the parabola has its focus at:
(-10,-7)
and directrix at:
x=16.
We need to determine the vertex of this parabola which is midway between the focus and the directrix.
Therefore the vertex will be at,
The equation of this parabola is of the form:
where p is the distance from the vertex to the focus.
Since the parabola opens towards the negative direction of the x-axis,
We substitute the vertex and the value for p to get;