I don't understand how my professor solved this problem. Can you please plug in values and show all steps thank you

PROBLEM 7: Using the diagram below find the angle of deviation of the exiting light beam Of if the index of refraction of the material is n.. = 150 30.09 Air 0,,: 90.0 - deg -80.0 . deg benzene mat . sin (0, ) =1 :in (61) sin (6) 61 = = asin 712 . -78.961 deg 90.0 . deg = 0, +0 + 30.0 - deg 0:90.0 - deg -0, - 30.0. deg = -18.961 deg