Hold your hand out with your elbow at your side and your forearm parallel to the ground. You should notice your bicep muscle flexing in order to keep your forearm in equilibrium in this position, working against the force of gravity. To maintain this equilibrium, how does the force that your bicep exerts on the forearm compare with the force of gravity acting on the forearm?

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⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j 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⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m