I think that it is established that Zoey drops out and leaves during the school year before the summer that he met Zoey. She has already turned 19 and only has one class left before graduation. I'm not sure, but it might be that Zoey isn't in the same class as MC but rather the year ahead of him which would explain the incongruity. If this isn't true, maybe she was held back a year at some point. What we do know is that she went no contact for six months before that summer, so she would have left fairly early in the school year.
Zoey is about 1 1/2 years older than he MC.
MC will be 19 years old while he is at B&R. Emma's Rooster Cluck was 6 months ago. So MC was 18 1/2 years old at that time. Zoey's birthday was at this time and she turned 20. Age clarified.
Zoey had to repeat a course in high school because she failed trigonometry. The MC even says so in the Interlude.
That's probably why Zoey had to do detention, and that's how she met the MC. The MC was 15 at the time, maybe 15 1/2, which would mean Zoey was 16 1/2 or already 17. Zoey taught the MC to smoke, so I assume Zoey was already 17 at the time of detention.
Since Zoey failed trigonometry and had to repeat, it could be that Zoey and the MC took the same trigonometry class.
It is interesting that Zoey's old friends from high school have graduated and may already be studying when the MC goes to B&R. Zoey's old friends are probably all around 20 years old.
Some have already compared Zoey to Quinn in terms of personality, and you can agree with that when you look at Zoey from detention, where the MC meets her. Zoey from Interlude has spent more time with the MC, and if there's one thing we know about the MC, it's that it can influence people in a positive way.
