7.5 I think because it can not be 9 because it’s not close to 50
The answer to the first one is sublimation.
The frequency of the wave has not changed.
In fact, the frequency of a wave is given by:

where v is the wave's speed and
is the wavelength.
Applying the formula:
- In air, the frequency of the wave is:

- underwater, the frequency of the wave is:

So, the frequency has not changed.
Answer:
both caused by physical vibrations
Answer:
Explanation:
Assuming school is at the end of the 20 mile route, then
20 mi / 35 mi/hr = 0.57142...hr
which is about 34 minutes 17 seconds