Answer
$(0,7)$
Work Step by Step
Standard form of a horizontal parabola is $x=a(y-k)^2+h$
Here, vertex:$(h,k)$ and $4a$ is latus rectum.
Since we are given $x=3(y-7)^2$
It can be written as:
$x=3(y-7)^2+0$
Compare the given equation with the standard form.
Thus, vertex: $(0,7)$