The formula for finding the velocity of a wave is to multiply its wavelength by its frequency. In this case, 30 m x 12 Hz = 360 meters per second.
In the case of light waves, the speed of light is constant. The wavelength and frequency of the component colors of light vary inversely, however. Red light has a longer wavelength and, therefore, a lower frequency than blue light, and infrared radiation has a longer wavelength than red light. Ultraviolet light has a shorter wavelength than blue light; therefore, its frequency is higher. X-rays and gamma rays have extremely short wavelengths and very high frequencies. They also contain far more energy than photons of visible light.