Answer:
Él/Ella trabaja en la escuela.
¿Tú compras el cuaderno en la escuela?
Step-by-step explanation:
In our first sentence, the verb is trabaja, meaning he/she/it works. This means that our subject can be either he or she, él or ella.
In our second sentence, the verb is compras, meaning you buy. The subject has to be you, which is translated to tú.
Hopefully this was helpful! :)