The general equation of a parabola with vertex (6,27) is y-27=a(x-6)^2, where a is a constant.
The y-intercept is when x=0, so y=-81=36a+27 and a=-108/36=-3.
The equation of the parabola is y=27-3(x-6)^2. When y=0 we have the x-intercepts:
3(x-6)^2=27; x-6=±3; x=9 and 3. So the intercepts are (9,0) and (3,0).