If I understand Dusty Miller's predictions right, she's saying that x20 will take the 3rd place and x30 will take the second. I can't be sure just yet if that's the case though.
Water Lily only marked x100. This means that every racer other than x100 will take a different place then their odds suggest - x100 will still be 5th, x10 will not be first, etc. This agrees with Dusty Miller's prediction, since x20 and x30 would take different places.
Nazuna marked x10, x20 and x30. Since x20 and x30 are the top 3, it checks out.
It seems x50 will win. As a backup, x30 can be bet on as well.