The man sitting next to Corey Simmons said he used to be a math teacher and started going over the worksheets in the middle of the train.
"Everything he got wrong or was confused about, he broke it down and corrected him," Wilson wrote in her Facebook post.
After the impromptu tutoring session, Simmons and the math tutor -- Wilson didn’t get his name -- got off the train at different stops.
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Simmons said that he’s about half way to understanding fractions, but there was something more important than math that came out of the chance meeting.
"You need help sometimes, and you shouldn't want to bite your tongue, to not ask for the help. So don't feel shy to ask someone for help. It's OK," Simmons told WCBS.