User blog comment:DiegoAnime3000/Just wanted to point this out./@comment-3146930-20140803131824/@comment-186.45.112.223-20140803142650

The thing is,the assumption that Glynda and Cinder are more or less the same age is probably incorrect.When talking about her age in relation to other characters Monty said that Cinder's 'older but not by much'.Since emerald and mercery are the age of normal students (17), Cinders probably in her early 20s

While Glynda is most likely just as old as Opzin who Monty decides as a 'old man' (Let's say late 40s)