Dear student
Refractive index (of a water wrt air)= speed of light in air/speed of light in medium=c/v1
Refractive index (of a glass wrt air)= speed of light in air/speed of light in medium=c/v2
so, Refractive index (of a glass wrt water)= speed of light in water/speed of light in glass=2.2*108 /2*108 =1.1
so, Refractive index (of a water wrt glass)= speed of light in glass/speed of light in water=2*108 /2.2*108 =0.9090
Regards