"See you at half past four!"
Translation:Dört buçukta görüşürüz!
Read the lesson notes: https://www.duolingo.com/skill/tr/What-time-is-it%3F
It includes a section about "half past".
The app does not have a "tips and notes" section. More frustratingly, one cannot enter the website through the phone! You can only find this section on the website (it is marked as a light bulb in skills that include it). Recently, they added it to the Spanish and Chinese courses (as far as I know). Whether or not they plan to include the rest of the courses is beyond me. For now, I think you should visit the website whenever you are learning a new skill.
It is kind of just the way that time works in Turkish :) Buçuk literally means "half," so it is like saying "at four and a half."
It is also would noting that the accusative case in "yediyi çeyrek" comes from the verb/adverb that goes with it. You would have to say "yediyi çeyrek geçe/yediyi çeyrek geçiyor" :)