Answered

A slinky is stretched across a classroom to 9 meters. A compression travels along the slinky at a velocity of 2 m s . How long does it take the compression to travel the entire 9m length of the classroom?

Answer :

AL2006
It really doesn't matter whether it's a compression wave in a Slinky®,
or a trained frog, or a model airplane, or a baby chicken.

Time = distance / speed

Time =  (9 m) / (2 m/s)  =  4.5 seconds 
it is simple. distance divided by time would make it letter c, 4.5 seconds