Given: The magnification +2.0 of a concave mirror of radius of curvature 60.0 $\mathrm{cm}$.
Focal length $=\frac{60}{2}=-30$
(-ve is taken because the focus of the mirror is behind the pole.)
Magnification, $\mathrm{m}=\frac{-\mathit{v}}{\mathit{u}}$
Putting the value of magnification in the above formula we get,
$\frac{-\mathit{v}}{\mathit{u}}=2$
$\mathit{v}=-2\mathit{u}$
$\mathit{v}$ is image distance, $\mathit{u}$ is object distance and $\mathit{f}$ is focal length.
Since,
$\frac{1}{\mathit{u}}+\frac{1}{\mathit{v}}=\frac{1}{\mathit{f}}$
Putting the values
$\frac{1}{\mathit{u}}+\frac{1}{-2\mathit{u}}=\frac{1}{-30}$
$\frac{1}{2\mathit{u}}=\frac{1}{-30}$
$\mathit{u}=-\frac{30}{2}\mathrm{cm}$
$\mathit{u}=-15\mathrm{cm}$
Hence, the object distance is $-15\mathrm{cm}$.