Answers:
a) 222.22 m/s
b) 800.00 km/h
Explanation:
The speed of a wave is given by the following equation:
Where:
is the speed
is the frequency, which has an inverse relation with the period 
is the wavelength
Solving with the given units:
This is the speed of the wave in km/h
Transforming this speed to m/s:

This is the speed of the wave in m/s
It doesn't matter where you are. "Tides" happen twice (hi - lo - hi - lo) in about 24 hours and 50 minutes. Anywhere.
If it doesn't do two complete cycles in 24 hours 50 minutes, then it's not tide.
Answer:
7
Explanation:
We are given:
w(x) = 3x - 7
w(x) = 14
The problem here entails us to solve for x;
To solve for x; equate the two expressions:
3x - 7 = 14
3x = 14 + 7
3x = 21
x = 7
So the value of x = 7
Answer: 529.9 Hz
Explanation:
Here we need to use the Doppler equation, so we have:
f' = f*(v + v0)/(v - vs)
Here, f is the frequency = 500Hz
v is the velocity of the wave, = 334m/s
v0 is the velocity of the observer = 20m/s
vs is the velocity of the source = 0m/s
Then we have:
f' = 500Hz*(334m/s + 20m/s)/(334m/s) = 529.9 Hz