97. For the first half of the journey, the motorcyclist traveled at a speed of 30 km/h, and for the second half - at a speed of 60 km/h. Find the average speed of the motorcyclist.
97. Let the entire distance be denoted as $a$ km. The motorcyclist spent $0.5a : 30 + 0.5a : 60 = a : 40$ hours on the entire journey. Therefore, the motorcyclist traveled at an average speed of 40 km/h.

## Puc. 9

![](https://cdn.mathpix.com/cropped/2024_05_21_a21e90374409a05a4ea7g-23.jpg?height=586&width=799&top_left_y=244&top_left_x=640)