Question

how do you answer Te gustan las clases? ¿Por qué? in spanish

Answer 1

It is basically asking you "do you like your classes, why?" you can answer with
"Me gusta (or No me gusta) las clases de ...... (insert subject, ex. matematica, biologia, quimica, etc.) porque..."
which means
"I like (or I do not like) the clases of....(insert subject) because .....)
Dont forget to add accents.