YOU SAID:

she was sixteen before

INTO JAPANESE

彼女は前に 16 歳

BACK INTO ENGLISH

She is before the 16-year-old

INTO JAPANESE

彼女は 16 歳の前にします。

BACK INTO ENGLISH

She was 16 years ago.

INTO JAPANESE

彼女は、16 年前でした。

BACK INTO ENGLISH

She was 16 years ago.