F1 Score for a Rare-Event Fill Classifier

A classifier predicts whether a limit order will be filled within one second. Of $10{,}000$ orders, only $200$ ($2\%$) are filled that fast. The model flags $300$ orders as 'will fill', and $120$ of those are actually filled.

What is the model's F1 score (the harmonic mean of precision and recall, with 'filled' as the positive class)? Give an exact fraction.