The Mother's Age

Thinking about this I realised the Mother is about 10+ years younger than Ted. When starts teaching he is about 31/32, we know this because he is 28 by the end of Season 1 and add 4ish years. Ted was teaching Economics 101, which I'm guessing would be a freshman course, but could be a later college class. I haven't been through college so I wouldn't know. Cindy, the roommate of the mother at one point, looked to be in her early twenties, so maybe the mother was too. I don't know. By my estimates and guessing the mother is about 10-12 years younger than Ted. Thanks for reading, and if you have any input please comment.