What is The speed of an electromagnetic wave is a constant 3.0 and times 108 ms. The wavelength of a wave is 0.3 meters.?

The speed of an electromagnetic wave is a constant 3.0 x 10^8 m/s in a vacuum. If the wavelength of a wave is 0.3 meters, you can calculate its frequency by dividing the speed of light by the wavelength. This would give you a frequency of 1 x 10^9 Hz.