Answer:
G. It will take twice as long.
Explanation:
Let's call
the original speed of the plane and
the distance between Dallas and Pensacola. The time the plane originally takes to complete the flight is

In this problem, we are told that the plane encounters wind moving at half of its speed:
, in the opposite direction. This means that the new speed of the plane is

And so, the time the plane takes now to complete the flight is

So, the plane takes twice the time as before.
I would think that you would have to do 42/2=21Hz, but I'm not sure...
Answer:
as far as the car can withstand
Explanation:
40 dB is 20 dB more power than 20 dB is. 20 dB more means 100 times as much.