n = \frac{{\sin {\rm{ }}i}}{{\sin {\rm{ }}r}} = \frac{{{\rm{depth}}}}{{{\rm{apparent depth}}}}

% MathType!MTEF!2!1!+-
% feaafaart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
% 4rNCHbGeaGqiVCI8FfYJH8YrFfeuY-Hhbbf9v8qqaqFr0xc9pk0xbb
% a9q8WqFfeaY-biLkVcLq-JHqpepeea0-as0Fb9pgeaYRXxe9vr0-vr
% 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaiaad6gacqGH9a
% qpdaWcaaqaaiGacohacaGGPbGaaiOBaiaabccacaWGPbaabaGaci4C
% aiaacMgacaGGUbGaaeiiaiaadkhaaaGaeyypa0ZaaSaaaeaacaqGKb
% GaaeyzaiaabchacaqG0bGaaeiAaaqaaiaabggacaqGWbGaaeiCaiaa
% bggacaqGYbGaaeyzaiaab6gacaqG0bGaaeiiaiaabsgacaqGLbGaae
% iCaiaabshacaqGObaaaaaa!5338!

Pasting the above "text" into MathType 5.0 will enter the above equation and make it possible to edit, save, and use in applications such as MS Word.