4. Brothers Petya and Vasya decided to shoot a funny video and post it on the internet. First, they filmed each of them walking from home to school - Vasya walked for 8 minutes, and Petya walked for 6 minutes. Then they came home and sat down at the computer to edit the video: they started Vasya's video from the beginning and Petya's video from the end (in reverse direction) simultaneously; at the moment when both brothers were at the same point on the path in both videos, they spliced Petya's video with Vasya's. The resulting video shows Vasya walking from home to school, and then at some point, he suddenly turns into Petya and walks backward home. What is the duration of the resulting video?

$[6$ points $]$

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# Problem 4.

Answer: 6 minutes.

Let $t$ minutes be the time from the start of the video until the brothers meet at the same point ($t$ does not have to be an integer). Then, from Petya's video, there were $6-t$ minutes left until the end of the viewing (i.e., until the start of the clip, since the video is playing in reverse). By concatenating the first $t$ minutes of Vasya's clip and the remaining $6-t$ minutes of Petya's, a video of $t+6-t=6$ minutes is obtained.