Why was the math book depressed?

This joke hinges on a delightful bit of wordplay, specifically a pun. The setup cleverly personifies a math book, suggesting it can experience human emotions like depression. The punchline then delivers the comedic twist by using the word "problems" in two different senses simultaneously. For a math book, "problems" are the exercises and equations it contains. But for a person feeling depressed, "problems" refer to life's difficulties and stressors. The humor arises from this sudden shift in meaning, creating an unexpected but perfectly logical (within the joke's twisted reality) reason for the book's despair.

Anyone who's ever cracked open a textbook can relate to the sheer volume of "problems" packed inside, sometimes enough to make a student feel a little blue themselves! The joke playfully flips this common experience, giving the book itself the blues. It taps into the universal dread of homework assignments and the often-overwhelming feeling of facing a daunting list of tasks. The absurdity of an inanimate object having feelings, combined with the all-too-real struggle with academic challenges, makes this a relatable chuckle for anyone who's ever wished their math book would just chill out.