Calculate the energy of a photon having a wavelength given

You'd use the equation that establishes a relationship between energy and wavelength, which looks like this

E=h⋅ cλ, where

λ - the wavelength of the photon;

c - the speed of light, usually given as 3⋅ 108 m/s;

h - Planck's constant, equal to 6.626⋅ 10 - 34 J s

Plug the value you were given for the energy of the photon in the above equation to get the wavelength

E=h⋅ cλ ⇒λ = h⋅c E

λ = 6.626⋅ 10 - 34 Js⋅3⋅ 108 m s - 1.257⋅ 10 - 24 J = 1.581⋅ 10 - 1 m