Hello Vaibhav

If you want to know the refractive index of the glass, I think the refractive index is 1.5.
Here is the solution, Let the apparent position of the silvered surface (in cm) = x
According to the property of plane mirror -
x+8 = 10+6-x
x= 4
Also, Refractive Index of glass = Real depth/ Apparent depth
which is 6/4 = 1.5

Hope this helps.
Good luck!