The verb from voy is ir, so answer # 2
First ¿Cuánto Cuesta? means How much in Spanish to answer correctly to that answer you say a number for an example:
Girl : ¿Cuánto Cuesta?
Guy: Tres
you may saw the object you are talking about.
But if you wan to answer as saying in terms like how much you love someone you say todo esto which means this much.
hi !!
Terminamos el examen ==> acabamos de terminar el examen.
acabar <em>present </em>
acabo
acabas
acaba
acabamos
acabáis
acaban
hope this helps :)
let's go to study - camos a estudiar