an upright image is a virtual image and it is expected to be on the same side as the object for a lens but not for a mirror.

magnification M = \(\frac{v}{u}\) = \(\frac{v}{2}\) = 3 ⇒⇒ v = 3u ( image is virtual = -3u)

using \(\frac{1}{f}\) = \(\frac{1}{u}\) + \(\frac{}{v}\) ⇒⇒ \(\frac{1}{u}\) - \(\frac{1}{3u}\) = \(\frac{1}{12}\)

 \(\frac{3 -1}{3u}\) = \(\frac{1}{12}\)

cross multiplying

24 = 3u = u = 8cm but v = 3u = 24cm

virtual image and object are at the side of the lens,

Hence, the distance between the object and the image = 24 - 8 = 16cm.