I don't mean to discourage you, as you should try the above methods and hope for the best. Per my personal experience, though, the yumas in the picture look really bad, and I haven't been able to save a single one that's gotten that bad. Telltale sign is the wide open mouth, which means that it's on its way out.
Put it in the shade in indirect light if you happen to have halides. Hopefully the place where you've gotten them have live arrival guarantee and you can get your $$$ back if things go south.
Good luck.