If the speed of light is 0.307 pc/yr, and there are 3.086X10^13 km/pc, what is the speed of light in km/hr? (pc=parsec) Please show work too! Thank you :)

What do electromagnetic waves carry? how are they produced through which media can they move? where do they transfer energy? what do they not transfer? what do mechanical waves carry? how are they produced? through which media can they move? where do they transfer energy? what do they not transfer?