It comes across as you are more interested in being angry than trying to understand what the original poster might have been saying(?)

> If it surprises anyone that a boy can ask a girl for help with maths, then that person is a sexist

I think everyone here agrees with you. My understanding of the original post's point was:

"I asked a girl for help in math and it was nothing special; Just like asking anyone who is good at math for help regardless of gender because we weren't socialized to view girls as somehow inferior here