if the person is speaking in such a colloquial way as to say 'wanna' then
no, not if you don't
I don't if you don't
fit the occasion.
If you want to go the whole hog:
Nuh. Do you?

Interested in Language
Please, teachers...
Could you help me with this?
I was wondering which ones are right.
Someone asks
- Do you wanna do this?
Someone else replies
1) I don't whether/if you don't as well/too.
2) no, if you don't
3) I don't if you don't
4) could you suggest a better answer?
Many thanks
if the person is speaking in such a colloquial way as to say 'wanna' then
no, not if you don't
I don't if you don't
fit the occasion.
If you want to go the whole hog:
Nuh. Do you?
Ok, I got it, David, thank you.
But if the person asks like this?
Do you want to do this?
What'd be the possible and formal answers?
Thank you very much.
"Not particularly, no. Do you?"