Annyeong-haseyo means what in english?
if someone asks you Annyeong-haseyo, what will you answer?

Question

Answer

Its the formal greeting of "hello".

Answer

Vkook and MinMyYoongi lol same! ARMY here ! :) 
And yeah, you can just say it back to that person. :)

Answer

Vkook - you made me giggle with your comment! (fellow ARMY here)

Answer

you don't know anneyonghaseyo?

Answer

Annyeong-haseyo means hello in korean. So I guess you just reply with 'annyeong-haseyo' back.