The xy-plane has a normal vector of 〈0, 0, 1〉, and any plane parallel to it will have the same normal vector.
Then the equation of the plane through (6, 3, 2) that is parallel to the xy-plane has equation
〈x - 6, y - 3, z - 2〉 • 〈0, 0, 1〉 = 0
==> z - 2 = 0
==> z = 2
