In a playful mood, the boyfriend teases his girlfriend, calling her over to the chalkboard to witness his 'magic'. She approaches, curious, and watches as he scribbles mathematical problems, talking her through the solutions with a smirk. She tries to play along, but her mock frustration turns genuine as she realizes she's not as smart as she thought. Her competitive spirit flares, and so does her lust, as she becomes hyper-aware of his body, his voice, his scent. She can't help but imagine him 'solving' her, his hands on her, his cock inside her, making her 'see' numbers and equations in her mind's eye as he fucks her senseless.