An object 5.0 cm

Here, Object distance, u = -20 cm (to the left of mirror)

Image distance, v = ? (To be calculated)

Radius of curvature, R = +30cm (It is a convex mirror)

So, Focal length, 

Now, putting these values of u and applying formula:

We get: 

Thus, the position of image is 8.57 cm behind the mirror (on its right side). Since the image is formed behind the convex mirror, therefore, the nature of image is virtual and erect.

Now,
For a mirror, Magnification, m =

So, m =  = + 0.42

Also, Magnification, m =

Where h₂= Height of image, h₁= Height of Object

So, +0.42 = 

h₂ = 0.42×5.0 = 2.1 cm

Thus, the size of image is 2.1 cm.