The mirror formula links object distance, image distance and focal length as \( \dfrac{1}{v} + \dfrac{1}{u} = \dfrac{1}{f} \), rearranged to \( v = \dfrac{uf}{u-f} \). Here the object distance is given as \( u = 15 \, \text{m} \); the focal length in the question is written as "\(f = l\, \text{m}\)", which is not a usable numeric value, so the image distance cannot be pinned to a single number and stays expressed as \( v = uf/(u-f) \) in terms of that focal length.