Stand and Deliver is a 1988 American drama film based on the true story of high school math teacher Jaime Escalante. Edward James Olmos portrayed Escalante in the film and received a nomination for Best Actor at the 61st Academy Awards. The film was added to the National Film Registry of the Library of Congress in 2011. Wikipedia
(Jaime is using girlfriends as the variables in an algebraic equation)
Raquel: Can you have negative girlfriends?
Jaime Escalante: No, only negative boyfriends. Forgive us, for we know not what we do.