Asprinter ran a 100 meter dash in 12.5 seconds. what was his speed? '

Speed is (pretty much) the same thing as velocity.

Velocity can be calculated by dividing the distance traveled over the time it took to travel said distance.

V=d/t

V=100 meters/12.5 seconds=8 meters per second

Velocity=8 m/s

Velocity 8 m/s

I really hope this helps ;D

wavelength variability is the right one