Angle of incidence / angle of refraction practice problems

Light travels from glass into diamond with an angle of refraction (θr) of 31.4 °. What is the angle of incidence (θi) if the refractive index of glass is 1.5 and the refractive index of diamond is 2.4.

The angle of incidence is: ° (Give your answer to the nearest 10th of a degree)