After all possible reflection and refractions the final image is located at a distance 'x' cm from air-glass interface. Then value of 7x is

Answer

`0010`

Explanation

Refraction plane surface `h' = h (mu_(r))/mu_(i)=(20xx3//2)/1=30 cm`
Mirror `1/v + 1/u=1/f`
`1/v+1/(-45)=1/(-10)`
`v=-90/7` from pole of mirror.
distance of object from plane surface `l=15-90/7=(105-90)/7=15/7`
Refraction at plane surface `x=10 l' mu_(r)/mu_(i)`
`x=l'15/7xx1/(3//2)=10/7 Rightarrow 7x=10` (location of final image from plane surface)