quote: Another mystery is how Planet Nine, if it is real, ended up on an orbit that potentially brings it as close as 280 AU and as distant as 1,120 AU, which is far beyond the realm of the other planets. For comparison, the outermost planet, Neptune, is 30 AU (2.8 billion miles, or 4.5 billion kilometers) from the sun. At 700 AU, Planet Nine would be 65 billion miles (105 billion kilometers) from the sun.
This one at space.com works
https://www.space.com/astronomy/solar-system/evidence-of-controversial-planet-9-uncovered-in-sky-surveys-taken-23-years-apart
quote: Another mystery is how Planet Nine, if it is real, ended up on an orbit that potentially brings it as close as 280 AU and as distant as 1,120 AU, which is far beyond the realm of the other planets. For comparison, the outermost planet, Neptune, is 30 AU (2.8 billion miles, or 4.5 billion kilometers) from the sun. At 700 AU, Planet Nine would be 65 billion miles (105 billion kilometers) from the sun.