Answer: 4 feet.
Step-by-step explanation:
A mirror reflects the image from the light it receives. I think it's useful to think of the surface of the mirror as a "portal." The distance between you and the mirror is 2 feet. So then your image also sits 2 feet behind the "portal" (the surface of the mirror). The general relationship can be described by 2d, where d is the distance between the object of interest and the mirror. This means if you were standing 4 feet away from the mirror, your image would seem to be 8 feet away.