Is it really correct to say "it is quarter to nine" as opposed to "it is a quarter to nine"? It sounds wrong to me.
I think both are acceptable and may vary with mood and speed of speech.
Here in Colorado, "quarter of" and "quarter to" and "quarter until" are all the same.
My answer: It's 8.45. No?!
It's a language learning system they aren't looking for number.
Eight forty-nine might be accepted, perhaps, except at this stage they're doing the quarter/half past/to approach. So they may only be accepting the equivalent English usage.