Asound wave has a wavelength of 0.450 meters. if its speed in cold air is 330 meters/second, what is the wave's frequency?

Most of the information's required are already given in the question. Based on those information's the answer can be easily deduced.
Wavelength of the sound wave = 0.450 meters
Speed of the sound wave = 330 meters per second
We already know
v=fλ
330 = f * 0.450
f = 330/0.450
  = 733.33 hertz
So the frequency of the wave is 733.33 hertz

Julia would be observing a. static electricity was caused by her sweater rubbing against her shirt and transferring electrons. she didn't touch anything metal, so that would cancel out b.she most likely didn't rub her sweater against her hair either, so that cancels out c.she also didn't scoot across the carpet while trying to take her sweater off, that cancels out d.so that leaves a.a. is correct.

Answer(b) both involve the use of levers;