The cities of Coco da Selva and Quixajuba are connected by a bus line. Buses leave Coco da Selva for Quixajuba every hour, with the first one departing at midnight on the dot. Buses leave Quixajuba for Coco da Selva every hour, with the first one departing at half past midnight. The bus journey takes exactly 5 hours.

If a bus leaves Coco da Selva at noon, how many buses coming from Quixajuba does it encounter during the journey?

![](https://cdn.mathpix.com/cropped/2024_05_01_d889f7c81233a28648eeg-1.jpg?height=226&width=317&top_left_y=1643&top_left_x=1506)

Figure 21.2

![](https://cdn.mathpix.com/cropped/2024_05_01_d889f7c81233a28648eeg-1.jpg?height=249&width=305&top_left_y=1943&top_left_x=1521)

Figure 21.3

![](https://cdn.mathpix.com/cropped/2024_05_01_d889f7c81233a28648eeg-1.jpg?height=220&width=214&top_left_y=2260&top_left_x=1566)

Figure 21.4
Let's observe that the bus departing from Coco da Selva to Quixajuba meets the buses that, at the time of its departure, are

Suggestion: Divide the coins into three groups of 16 coins. on the way from Quixajuba to Coco da Selva and the buses that depart in the next five hours.

The buses that are on the road are those that departed up to 5 hours before this bus, while the buses that are yet to depart must do so within 5 hours after. Thus, the bus will meet all those that departed from Quixajuba between 7:30 AM and 4:30 PM, which are 10.