In the early minutes of the film Parasite, when you’re learning about the family the story is centered on, they show a wall of family pictures and the first number shown is 474, on the character who is the mother of the family. As often is the case, the 47 is displayed, the mirror of 74.

And not much further into the film, the son of the mother begins tutoring a wealthy daughter on the subject of English, and he asks her to begin with problem #38.