Given: The magnification +2.0 of a concave mirror of radius of curvature 60.0 cm.
Focal length =‌

60

2

=−30
(-ve is taken because the focus of the mirror is behind the pole.)
Magnification, m=‌

−v

u

Putting the value of magnification in the above formula we get,
‌

−v

u

‌=2
v‌=−2u
v is image distance, u is object distance and f is focal length.
Since,
‌

1

u

+‌

1

v

=‌

1

f

Putting the values
‌

1

u

+‌

1

−2u

‌=‌

1

−30

‌

1

2u

‌=‌

1

−30

u‌=−‌

30

2

‌cm
u‌=−15‌cm
Hence, the object distance is −15‌cm.