Answer:
The frequencies are

Step-by-step explanation:
From the question we are told that
The speed of the wave is

The length of vibrating clothesline is

Generally the fundamental frequency is mathematically represented as

=>

=>

Now this other frequencies of vibration experience by the clotheslines are know as harmonics and they are obtained by integer multiple of the fundamental frequency
So
The frequencies are mathematically represented as

=>

Where n = 1, 2, 3 ....