AIBU to ask how you handle those low level, every day sexist comments?

[ChristmasFairy2018]

At a work meeting today I was talking to a woman (in her 20s) who asked me (in my 50s) how she could handle sexist comments in the workplace.

She'd just done a piece of work which meant attending conferences to network; when she tried initiating conversations with some of the male delegates a number were incredibly rude to her. Things like implying she did not know her subject area or that she was wasting their time,.
What advice would you give her? How do you stay professional but not let someone get away with it?

Know more than them. And demonstrate it. I particularly like being patronized then mentioning that they can attend the session I'm facilitating on the subject.

And honestly, when it's bad and I can't be arsed, I do about 30 seconds of womansplaining at the beginning. Long words, lots of technical terms, even invade their space a little, subtly. Can't beat 'em, join 'em. Horribly, it works.