The English is wrong - it should read 'where did you use to live' (not 'did you used to live') so my translation from the Welsh ( Ble o't ti'n arfer byw?' ) is correct.
Both are used ("did you used to" and "did you use to").
In that case my answer should have been marked as correct
Probably. Please use the "Report a problem / My translation should be accepted" feature to bring the missing alternative to the attention of the course maintainers.
I have done