The term "Planet X" has been used historically to refer to hypothetical planets beyond Neptune. These hypotheses have been disproven or remain unconfirmed.

Therefore, it is impossible to determine the distance of a non-existent planet in astronomical units.

If you're interested in the distances of known planets, here are their average distances from the Sun in astronomical units (AU):

* Mercury: 0.39 AU

* Venus: 0.72 AU

* Earth: 1 AU

* Mars: 1.52 AU

* Jupiter: 5.20 AU

* Saturn: 9.58 AU

* Uranus: 19.22 AU

* Neptune: 30.07 AU