A car travels 20 meters east in 1.0 second and then travels
10 meters west in 20 seconds. The
displacement of the car at the end
of this 3.0-second interval is-

a displacement distance is size of displ

snell's law

refractve index = sin incidence / sin refraction

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