What is the equation to find wavelength of red light with a frequency of 4 x 10^14

If you know the frequency, then the equation to find the wavelength

of ANY wave is

Wavelength = (wave speed) / (frequency).

Since we're talking about light, we'll use 3 x 10^8 m/s for a speed.

Wavelength = (3 x 10^8 m/s) / (4 x 10^14 / sec) =

7.5 x 10^-7 meters =

750 nanometers