The question can't be answered with the given information.
We don't know how y changes when x and z change.
That information would be given in the form of an 'equation',
of which there is none to be found here.
For example, the equation might be: y = 9x/z .
Then, as you said, y=-99/4 when x=-11 and z=4,
AND
when x=2 and z=-8, y would be -2.25 .
But, the equation might be y = (x-88)/z.
Then, y is still -99/4 when x=-11 and z=4,
BUT
when x=2 and z=-8, y would be 10.75 .
With only the information given in the question,
there's no way to be sure.
