Traslacion: In the afternoon I have two classes.
Por la tarde yo tengo dos clases. (Correct answer)
Traslacion: In the afternoon I have two backpacks.
Por la tarde yo tengo dos mochilas.
In the afternoon I have two useful.
Por la tarde yo tengo dos útiles.
Traslacion: In the afternoon I have two pencils.
Por la tarde yo tengo dos lápices.