A near UV photon of 300 nm is absorbed by a gas and then re-emitted as 2 photons. One photon is red with wavelength 760 nm. Hence wavelength of the second photon is:
496 nm
λ = 300 nm
λ1 = 760 nm
λ2 = ?
Since the total energy has to be constant - hν is constant, ν = cλ
Use the formula: 1λ=1λ1+1λ2