Hot girl from class, talked to her a couple times and flirted a bit on FB.

I ask her for drinks on Monday night around 8 and she said "We have school the next day tho... I start at 8 0_0"

She hasn't said "I'm working" which is an answer I can't do anything about. It's like she's asking to be convinced/testing my frame/shy. Is this possible?

What's a good reply?