7.2. Vasya left the village of Vasilki and walked to the village of Romashki. At the same time, Roma left the village of Romashki for the village of Vasilki. The distance between the villages is 36 km, Vasya's speed is 5 km/h, and Roma's speed is 4 km/h. At the same time as Vasya, Dima left Vasilki on a bicycle at a speed equal to the sum of the boys' speeds and headed towards Roma. When he met Roma, he greeted him and immediately turned back. Meeting Vasya, he greeted him and immediately turned back. And so he rode back and forth between the boys until they met. How many kilometers did the cyclist travel during this time?
7.2. Dima the cyclist was traveling at a speed of $5+4=9$ km/h for as long as it took Vasya and Roma to meet. Both of them walked 9 km in an hour. Therefore, the total time spent on the journey was $36: 9=4$ hours. In this time, the cyclist traveled $9 \cdot 4=36$ km. Answer: 36 km.