This photo of two subway passengers sharing a moment of compassion is going viral for all the right reasons.

Corey Simmons had been taking advantage of his lengthy New York City train ride to study up on mathematics. His son, who is in the 3rd grade, was having trouble with fractions – so Simmons took it upon himself to relearn the formulas.

But considering it has been almost 30 years since Simmons had to do elementary school math, he was having trouble with some of the problems.

As he was studying on the subway, however, a man sat next to him and asked what he was doing.

Simmons explained how he was trying to relearn fractions so he could help his son in school. The other man then said that he used to be a math teacher and he would be more than happy to help Simmons.

A nearby subway passenger named Denise Wilson overheard the exchange, snapped a photo of the two men, and posted it to Facebook.

"[Simmons] asked the guy to quiz him and everything he got wrong or was confused about, he broke it down and corrected him," says Wilson. "By the end of my train ride, [Simmons] had a better understanding."

Though the math teacher left before anyone could catch his name, Wilson was struck by how inspiring the interaction had been.

"I started tearing up," Wilson told CBS. "It was just one person helping another, and I thought that was beautiful."

(WATCH the video below or international viewers can watch the video on the CBS News website)

By Our Calculations, Your Friends Would Love This Story: Click To Share – Photo by Denise Wilson