8.1. Five buses stand in a row behind each other in a traffic jam, and in any two of them, there is a different non-zero number of passengers. Let's call two different people sympathizers if they are either in the same bus or in adjacent ones. It turned out that each passenger has either exactly 20 or exactly 30 sympathizers. Provide an example of how this can be possible.
Solution. For example, let there be 12, 9, 10, 2, and 19 people in the buses respectively. This example is not unique. It is easy to construct if you realize that on average, there should be 10 people in a bus. Indeed, there should be 21 or 31 passengers in the first two buses and in the first three buses. Therefore, there are 21 people in total in the first two buses, and 31 in the first three.

Criteria. Any correct example - 7 points.

Only noting that there are 21 or 31 people in consecutive buses - 1 point. Only noting that on average there are 10 people in a bus - 3 points.