your guess is as good as mine
US /jʊər ɡɛs ɪz æz ɡʊd æz maɪn/
UK /jʊər ɡɛs ɪz æz ɡʊd æz maɪn/

1.
tekaan anda sama baiknya dengan tekaan saya, saya pun tidak tahu
used to say that you do not know the answer to a question, or do not know what is happening, for the same reason as the person asking
:
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Why did he leave so suddenly? Your guess is as good as mine.
Mengapa dia pergi begitu tiba-tiba? Tebakan anda sama baiknya dengan tekaan saya.
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When will the new policy be implemented? Your guess is as good as mine.
Bilakah dasar baru akan dilaksanakan? Tebakan anda sama baiknya dengan tekaan saya.