The frequency of a wave is the number of vibrations per second. The problem already states that the wave has a frequency of 60 vibrations per second.

Here's why the information about the wave traveling 30m in 1s is irrelevant:

* Frequency is independent of speed: The speed of a wave tells you how fast it travels, but it doesn't change the number of vibrations it makes per second.

Let me know if you have any other questions!