The speed of a light wave c is related to its wavelength λ and its frequency f by

C=λf. If the speed of light is 3 × 10^8 meters/second and the wavelength of an infrared wave used in a remote control is 7 × 10^-9 meters, then what us it's frequency

A) 2 × 10^-17 Hz
B) 2 × 10^0 Hz
C) 4 × 10^16 Hz
D) 4 × 10^-2 Hz

c = wf

3e8 m/s = 7e-9*f
Solve for f.
Post your work if you get stuck.