"Mereka tidak baik."

Translation: They are not good.

[waltcamp45]

"They are not well" should be acceptable as ... well.

[lili114354]

i wondered about this too!

'mereka tidak sehat' could be 'they are not well', as in healthy well.

but if you wanted to say 'they are not well', as in doing well generally, i'd have thought 'mereka tidak baik'...

[DavidHarri227108]

Can someone clarify the range of meanings which 'baik' covers? Thanks!

[Away54]

The close meaning for Mereka tidak baik: they have bad attitude/influence. It's often said by our parents to warn us from some commingling.

"Jangan dekat-dekat dengan mereka! Mereka tidak baik."

[zarabi13]

why is it tidak and not bukan?

[boringtomi]

because you're negating an adjective. Negating a noun would use bukan, negating an adjective or verb would use tidak

[Keith_APP]

baik = bagus?

[Phil314382]

"They are not GOOD"
"Ther are not OK"
These all should be accepted.
There is no definitive meaning of "Biak" so to place s definitive meaning in the answer is wrong.
Duolingo please have a look.