The other tutor got the vertex wrong.

Let's draw the directrix line and the vertex:


The vertex is halfway between the focus and the directrix. 
We draw a green line from the focus to the directrix



That green line is 5 units long, so the midpoint of the green line,
which is the vertex, is  units from the directrix and the 
focus.  So the coordinates of the vertex is (,9) or
(,9)




To sketch in the parabola we construct two squares, one on each side of
the green line from vertex to focus:



Now we can sketch in the parabola with the vertex and which passes
through the corners of those two squares:




The equation of the parabola which opens right or left and has vertex (h,k) 
is given by:



where p is the  or  unit distance between the 
directrix and the vertex, and also the same distance from the vertex 
to the focus.  p is taken positive if the parabola opens right, and 
negative if the parabola opens left.

This parabola opens right so , and with the vertex
(h,k) = (,9)





That's the equation of the parabola in standard form.

Edwin