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If you don't study, you'll fail the exam.
Literal
Study don't-do [if-と] exam [on-に] fail [warning-よ].
Uses the colloquial conditional ~ないと — the negative stem plus と creates 'if you don't X,' with the consequence stated explicitly rather than left implied. The sentence-final よ adds a warning tone, making this sound like a parent or friend's admonition rather than a neutral prediction.