Speed and medium are properties of a wave which is in common within an area of the spectrum of the visible light. i.e;
Their medium of propagation They both travel at the same speed ( speed of light )The properties mentioned above are properties which define that wave is found within an area spectrum for visible light
What are electromagnetic waves?These are waves which that are propagated or produced as a result of vibrations between an electric field and a magnetic field. Electromagnetic waves such as radio, microwave, visible light, ultra-violet, x-rays and many more; travel at the same speed.
Learn more about electromagnetic waves:
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My guess would be 14 years old?