"Meet me at the library at 7 PM. I need your help with a mystery."

Alex's curiosity was piqued. He arrived at the library, and Rachel was already seated at a table, surrounded by stacks of math textbooks and papers. She handed him a worn-out copy of "Problems in Mathematics" by V. Govorov.

It turned out that Jack had been creating his own problem sets using Govorov's book and was using the missing solutions as a way to challenge his classmates. He had been secretly modifying the PDF file and sharing it online, where it had been downloaded by other students.

Alex nodded. "Yeah, I've used it to prep for my math exams. It's a great resource."

From that day on, Alex, Rachel, and Jack formed an unofficial study group, tackling tough math problems and exploring the depths of "Problems in Mathematics" by V. Govorov.

She led Alex to a nearby computer lab, where they began to dig deeper. After some sleuthing, they discovered that the 'missing' solutions had been deliberately erased by none other than their classmate, notorious for his love of puzzles and mischief, Jack.

The three of them spent the rest of the evening working on a new set of problems, using Govorov's book as inspiration. As they collaborated, Alex realized that sometimes, the best way to learn mathematics is by working with others and embracing the challenges that come with it.

Rachel explained that she had been working on a specific section, "Equations and Inequalities," but when she returned to her notes, some of the solutions to the problems were missing. She suspected that someone might have been playing a prank on her, but she needed Alex's help to figure out who and why.

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