Last question i'm stuck on please help me through this.

Question

Five waves pass a dock in 2.0 s. If the waves are traveling at 10.0 m/s, then what is the wavelength of the waves?

Answer 1

4m

Answer 2

how did you get 4m?

Answer 3

v = d/t
d = v*t
d = 20m/s
5 waves

Answer = 20meters/5

Answer 4

ok, thank you for explaining