u=−60‌cm‌ and ‌f=20‌cm
From the lens formula, we have:


‌

1

v

−‌

1

u

‌=‌

1

f

‌

1

v

‌=‌

1

f

+‌

1

u

‌=‌

1

20

+‌

1

−60

‌=‌

3−1

60

=‌

2

60

=‌

1

30

v‌=+30‌cm
The positive sign indicates that the image is formed at the right of the lens.


The image I1 is formed behind the mirror and acts as a virtual oject for the mirror. The convex mirror forms the image I2, whose distance from the mirror can be determined as:

‌

1

v

+‌

1

u

‌=‌

1

f

Here, u‌=15‌cm
and, f‌=‌

R

2

=10‌cm
‌

1

v

‌=‌

1

f

−‌

1

u

v‌=30‌cm
Hence, the final virtual image is formed at a distance 30‌cm from the convex mirror.