Given: u=12‌cm (negative), f=8‌cm (positive)
We know, by lens formulae,
‌‌

1

f

=‌

1

v

−‌

1

u

‌‌

1

v

=‌

1

u

+‌

1

f

or ‌

1

v

=‌

1

u

+‌

1

f

or ‌‌

1

v

=‌

1

−12

+‌

1

8

‌‌

1

v

=‌

−2+3

24

=‌

1

24

∴‌‌v=24‌cm‌ (positive) ‌
Thus, the image is formed at a distance of 24 cm behind the lens.
We know, ‌‌m=‌

v

u

=‌

24

−12

=−2
Thus, the image is Real, inverted and magnified in size.