"Saudara dan saudari saya pergi ke Jepang."

Translation: My brother and sister are going to Japan.

[IlseDens]

Is there a difference between "abang" and "saudara" ?

[graeme143846]

Why would .. will go .. not be accepted.. would have thought its means the same as .. are going ...

[Mal205614]

In my Indonesian tutor book, saudara is given as a formal title (meaning SIr or Mr) with the similar uses as Pak. Not brother.

[Rick392366]

Yes, it can be used like that, but that is not the only meaning of this word.

KBBI definition:
https://kbbi.web.id/saudara

saudara/sau·da·ra/ n
1 orang yang seibu seayah (atau hanya seibu atau seayah saja); adik atau kakak;
2 orang yang bertalian keluarga; sanak:
3 orang yang segolongan (sepaham, seagama, sederajat, dan sebagainya); kawan; teman:
4 sapaan kepada orang yang diajak berbicara (pengganti orang kedua):
5 ki segala sesuatu yang hampir serupa (sejenis dan sebagainya):
6 ki tembuni:

Your Indonesian tutor book is referring to the 3rd or 4th entry above.