I am guessing by what I had it is a plz don't quote me on that I could be wrong
It's hard to tell exactly what's happening in that 110 cm that you marked over the wave. What is under the ends of the long arrow ? How many complete waves ? I counted 4.5 complete waves ... maybe ?
If there are 4.5 complete waves in 110cm, then the length of 1 wave is (110/4.5)=24.44cm.
Frequency = speed/wavelength
Frequency = 2m/s /0.2444m
Frequency = 8.18 Hz
Answer:

Explanation:
Given data
Average intensity of sunlight on one day I=700 W/m²
Power P=170 W
To find
Area A
Solution
As we know that:

8.33 m/s
Explain:
If you understand what 1 km = 1000 m and 1 hr = 60*60 seconds signify, you already know what they mean. If you translate 1000 m/ 3600 s to km/hr, you'll get 5 m/ 18 s, which you can multiply by 30 to get (30 x 5)/18 = 8.33 m/s.