What a stupid sentence this is!
This sentence is supposed to be a joke, but a serious translation "다음 주 토요일은 무슨 날이야?" is also accepted.
이건 좀....말이 안 돼요...
이게 무슨말인지...
다음주 토요일은 며칠이야? is right..
Im guessing Saturday?
'만두 천원어치 얼마에요?' 같은 소리하고 있네요.
토요일 doh!
... WHAT KIND OF QUESTION IS THIS???
It's correct in English, but it doesn't make any sense in Korean. It should be 다음 주 토요일은 무슨 날이야? or 몇일이야?
"다음 주 토요일은 무슨 날이야?" is accepted, but 몇일 is not a word. Maybe you want to say 며칠?