A thick glass mirror produces a number of images.
There is an apparent shift of actual silvered surface toward the unsilvered face.
Effective distance of the reflecting surface from unsilvered face =dμ=33/2cm=2 cm
Distance of the point object from effective reflecting surface =9 cm+2 cm=11 cm.
Distance of image from the point object =11 cm+11 cm=22 cm
Distance of image from unsilvered face
=(22−9)cm=13 cm.