the chapter you were referring to with Xia's age was on ch4, he said he's 120y.o.... also, simple details like this are common illness in manhua called contradiction (every manhua title i've read has them, havent encountered a single manhua that doesnt have missed details or contradiction), this series has a lot, almost every chapter, from one panel with Bai holding Xia's left arm then next panel he's holding his right arm... honestly I am getting more and more disappointed rather than getting excited because of all these small details that always missed, this rarely in happen in manhwa and manga...
Next Chapter
Doo Joon will face that teacher, but of course this time, Doo Joon is giving a more strict and colder gestures (not evil - but almost like one, which is understandable), the teacher just couldn't help but tremble since this time, he can negotiate... Hee Won and Doo Joon finally had their vacation in Jeju Island, the sad part is, the niece is with them along with that childhood BF, ahahahaha ╮( ̄▽ ̄)╭