The image formed by a convex mirror of focal length 30 cm is one quarter of the size of object. The distance of object form the mirror is

90 cm

$M = - \frac{v}{u} = \frac{1}{4}$

$ v = -\frac{u}{4}$

$ \frac{1}{v} + \frac{1}{u} = \frac{1}{f}$

$ \frac{-4}{u} + \frac{1}{u} = \frac{1}{30}$

$ \frac{-3}{u} = \frac{1}{30}$

$\Rightarrow u = -90cm$