A point object is placed in front of a thick plane mirror as shown in Figure. Find the location of final image w.r.t. object.

Mirror can be shifted to new position C'D' . Distance are shown in figure.  Image will be at equal distance from the mirror C'D' as the object is.Image distance from C'D'  is  10+53/2=10+103=403cmSeparation between object and image is =803cm .