The vertex of a parabola is at $(6,5)$, and its axis of symmetry is vertical. One of the $x$-intercepts is at $(8, 0)$. What is the $x$-coordinate of the other $x$-intercept?

Using the symmetry of the parabola, the other x-intercept is at (10,0), so the answer is 10.

The axis of symmetry is the line: x = 6.

Since one of the x-intercepts is (8,0) which is to the right of the line of symmetry,

the other intercept will be to the left of the line of symmetry: (4,0).