An object is 80cm in front of plane mirror’M’. If the object is moved 0.20 m away from the mirror, how does the image shift from its previous image?

Dear Student,
Distance of object from the plane mirror = 80 cm
Distance between the object and its image,
= 80 + 80 => 160 cm (plane mirror make image of the object at same distance where object is placed but behind the mirror)
Now,
New distance of the object from the mirror,
= 80 cm + 0.20 m or 20 cm 
= 100 cm
Distance between object and the image,
= 100 + 100 => 200 cm 
Image shift = 200 - 160 => 40 cm
Regards