The question can be found here: http://gyazo.com/fc4d26cd35e6ce368ad2a8ed504f1dcc
The refractive index it references can be found here: http://gyazo.com/94fd2f3b5ea7da9226c3acd56b0024c1
I'm not really sure where to get started on the "showing" part of the question. I anticipate that Snell's Law will be used somehow. I'm not looking for a full answer, just a push in the right direction.