The opera station broadcasts at 90.5 mhz and the rock nroll station at 07.1 mhz which station's signal has waves with longer wavelengths and which one has
higher energy

I'm assuming that's a typo, and the rock station is at 107.1 MHz .

The lower frequency radio waves, emanating from the opera
station, are longer.

Each photon of radiation with higher frequency, emanating from
the rock station, has more energy.  But the total energy radiating
from each station depends on the power level of their transmitter,
not on their frequency.
 

482.8032 km per hr

Explanation: 300 * 1.609344 =