We already know the formula for finding the energy of a photon with this wavelength as:
E = ħc / λ
The information's that we already know are:
h = Plancks constant
= 6.626x10^-34 Js
c = light speed
= 2.999x10^8 m/s
λ = Wavelength of the light as given in the question
= 670.8x10^-9 m
E = amount of energy
Then
E = (6.626x10^-34) * (2.999x10^8)/ (670.8x10^-9)
= 2.962x10^-19 J
