simple reflection

juz imagine....

if u stand 2m in front of the mirror,, then u will see ur own reflection(in the mirror) also stands 2m from the front of the mirror,, right?

so,, if people were to ask, wt is the distance between u and ur own reflection? then u know that the distance is 4m

same for ur question.
U are moving away from the mirror at a speed of v,
and at the same time, ur reflection is moving away at the same speed.

it makes 2v the right answer

you are moving away from the mirror at a rate of V
your image are moving away from the mirror at a rate of -V (opposite direction)

so your image are moving away from you at V - (-V) = 2V.