Please help me with a question: calculate the speed of light inside the plastic prism using this measurement of n from the slope!

Plastic Prism Angle of incidence Angle of reflection Angle of refraction 10 20 1350 30 290 40 25.50 50 500 310 60 35. 50 70 3 90 80 80 420 . Slope of sin (01) vs. sin(0, ) : ..... What is the expected slope? .. % error = . % error of np compared to the accepted value 1.5 = .. 65. 52% . Critical angle: 0c = ..! !. ; mp = 1/sin(60) =1516 % error of np compared to the accepted value 1.5 = .. 0 , 1 41. 2 sinoe= 1.52 1