If the distance from the Earth to the moon is 3.84 x 105 km. How long would it take a radio wave with wavelength 413.8 m to travel from Earth to the moon?

Question

C=(lanbda)v & E=(h)v

Answer 1

You don't need either of these equations.
The speed of the radio wave is 3E8 m/s. You have a distance of 3.85E8 meters (note I converted from km to m).
distance = rate x time.
You have distance, you have rate (3E8 m/s), solve for time in seconds.