Gamma-ray bursters emit pulses of gamma rays with high energies. the frequency of the most energetic pulses has been measured at around 3.0 x 1021 hz. what is the wavelength of these gamma rays?

The horizontal blue line through the middle of the lens is called the optical axis. as the lamp is moved above or below the axis, keeping the horizontal distance to the center of the lens constant, how does the horizontal distance from the lens to the image change?