Is not completing all given challenge is Declined?

Question

I've challenged my friend which he dont wanna lose, so before he lost, he get out from the challenge and dont answer it (at question 3). At the end, the challenge declined, and there is no losing exp for him. Is it fair?

Answer 1

If you leave the challenge until time is over... The challenge gets expired.. (if you don't answer any of the questions)

If you answer any question and then don't answer the remaining... The remaining questions will be considered incorrect...(but after the challenge time expires)

Answer 2

As far as I know, when someone leaves the challenge in the middle the remaining answers (not given) are considered incorrect and there shouldn't be the option to decline anymore.
I've never left a challenge, but some my opponents have and I saw that I won that challenge.
Maybe there's some bug in the app

Answer 3

For the next questions, the answer is incorrect