"For how many years did František sell cars?"

Translation: Kolik let prodával František auta?

[Jean290771]

možná by mohl být použit průběhový čas minulý, ne?

[kacenka9]

yes

[BrinoPua]

The english sentence sounds to me like he has stopped selling cars, in which case shouldn't the perfective Prodal be used?

[VladaFu]

No, that would be wrong. That would be selling all in one go and than you can't ask for how many years was he doing it. It must be imperfective, it was a continuous action (selling cars).