Ta！ A bean-sized sweat dripped on the exercise book and burst into a small flower. The bright desk lamp makes this black-and-white math problem more dazzling. XX frowned and stared at the math problem unblinkingly. A drop of sweat flowed down his eyebrows to the tip of his nose. He paid no attention and stared at the problem motionless. Suddenly, he seemed to realize that he was writing on the draft paper, but immediately stopped, his eyebrows were unlocked, his eyes were wide open, and the lines on his head were exposed, as if he could not solve the problem himself. He stood still for a few minutes, as if he had suddenly discovered a new continent, and his black strokes appeared on the draft paper. His expression is no longer dignified, but gradually relaxed, haha! I solved it! He couldn't help crying. Instead, he smiled confidently.