I racked my brain for almost 10 minutes, until suddenly,
it hit me !
You're breathing one right now ! So am I .
Air is a mixture of a lot of elements.
Nitrogen, Oxygen, and Argon account for 99.964 percent.
The other 0.036 percent is mainly Neon, Helium, Krypton,
and Hydrogen ... more elements.
Then there are Carbon Dioxide and water vapor.
Yes, those are compounds. But together, they add up
to very little of the air we breathe, and if both of them
suddenly disappeared, we would hardly notice it.
Answer:
The frequency of the beats is 43.6408 kHz
Explanation:
Given:
f = frequency = 39.6 kHz
vc = speed of the car = 35 m/s
vs = speed of the sound = 343 m/s
Question: What is the frequency of the beats, f' = ?
As the car moves towards the source, the frequency of the beats

These values when compared seem to be the same. They are equal. If we convert them to the same units, they results to the value which is:
51.5 Hectograms = 5100 Grams
51,500 Decigrams = 5100 Grams
Hope this answers the question. Have a nice day.