The vertex of a parabola is at $(12, -4)$, and its axis of symmetry is vertical. One of the $x$-intercepts is at $(15, 0)$. What is the $x$-coordinate of the other $x$-intercept?
If the vertex is (12, -4) and one of the x intercepts = (15, 0)
By symmetry.......the other x intercept is given by 12 - ( 15 - 12) = 12 - 3 = 9
