Answer: estudiabas
Después de la escuela, tú estudiabas mucho, pero mi hermano, no.
After school, you studied hard, but my brother, no.
Explanation: The subject in this sentence is "tú", that is a second-person in the singular, so the verb must be conjugated in this form. Tú estudiabas.
[tex]\textit{\textbf{Spymore}}[/tex]
