the magnification of a mirror is +2/3. What type of mirror is it?

The mirror is a convex mirror as convex mirror always forms a virtual erect and diminished image of an object since magnification is less than 1 therefore the image formed will be diminished and we know that concave mirror produces virtual image in only one case and that is also enlarged one so the answer is convex mirror
NOTE THAT WHEN MAGNIFICATION IS GREATER THAN 1 THEN IMAGE FORMED WILL BE ENLARGED