1.1. At the stadium, through the checkpoints numbered 1, 2, 3, and 4, an equal number of fans entered. They then passed through several more checkpoints, moving along the arrows, and at the fork, the fans were evenly distributed. At checkpoint 7, 15 people passed the control.

![](https://cdn.mathpix.com/cropped/2024_05_06_577f9e55f1dbdd46be53g-1.jpg?height=582&width=1057&top_left_y=286&top_left_x=91)

How many people passed through checkpoint 8?

Checkpoint (control and pass point) - a place where stadium staff check fans for tickets and prohibited items.
Answer: 24

Solution. Let $2x$ people pass through each of the first four checkpoints. Then, through checkpoint 7, $2x$ people passed from the first two checkpoints and $x$ from the third, totaling $5x=15$ people, from which $x=3$. Therefore, each of the first four checkpoints had 6 people, and checkpoint 8 was passed by everyone who entered through the first four checkpoints, which is 24 people.