note the distance between the x-coordinates is 3 ... so, the x-coordinates for the other two points have to trisect this component length of 3. 3/3 = 1 ... the x-coordinates must be 4 and 5.

do the same for the y and z coordinates.

y-coordinates will be 6/3 = 2 units apart

z-coordinates will be 9/3 = 3 units apart