What kind of an image is formed when an object is placed in front of a plane mirror?

1. Virtual image

2. Real image

3. Enlarged image
   

4. Equal sized image

A plane mirror forms a real image of an object placed in front of it.

An object is placed in front of a plane mirror at a distance of $10cm$. The image formed behind the mirror will be at a distance of

An object placed $20cm$ in front of a mirror is found to have an image $15cm$ in front of it. Find the focal length and the kind of mirror used?