Awave has a wavelength of 20 mm and a frequency of 5 hertz. what is its speed?
a. 100 mm/s
b. 100 hertz/s
c. 4 mm/s
d. 25 mm/s

Speed = Wavelength * Frequency 

S = 20 mm * 5 /s

S = 100 mm/s

In short, Your Answer would be: Option A

Hope this helps!

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.