Inscribed Polygon Problems II Exercise


I do not understand the solution. If Octagon’s angle POQ=45 & Dodecagon’s angle POR=30 degrees, then shouldn’t it be that the difference between the two of them is 15 degrees? Why is it 30 degres? In the video, greg shows a similar problem & there he just subtracts. What am I missing here?

Hint: largest difference. The solution does talk about why 15 degrees do not work.