Can't the second "mereka" be dropped? The subject is already known...
I agree! I've had the same thought.
I find this somehow weird, in English we say they go there or they left here, but they donot go to school . Not they go from here... Which is illogical
Would "Mereka tidak ke sekolah" work without the first part of the sentence?
Yes, it works as well without the first part of the sentence. The verb "pergi" can be dropped here. Something like this :
Mereka ke mana ? Mereka tidak ke sekolah. Mereka ke pantai.
Why is there only one pergi?