optics good

a paralle beam of light falls normally on the first face of a prism of small angle. at the second face it is partly reflected and partky transmitted, the reflected beam striking the first face again, and emerging from it in a direction making an angle 6degrees 30 minutes with the reversed direction of the incident beam.the refracted beam is found to have undergone a deviation 1 minute 15 degrees from the priginal direction. find the refractive inex of the glass and the angle of the prism.