Object is placed at distance 2$f$ from the lens. So first image $I$ will be formed at distance 2$f$ on other side. This image $I_1$ will behave like a virtual object for mirror. The second image $I_2$ will be formed at distance 20 cm in front of the mirror, or at distance 10 cm to the left hand side of the lens.

Now applying lens formula

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




$\therefore \frac{1}{v}-\frac{1}{+10}=\frac{1}{+15}$

$\mathrm{o}\mathrm{r} v=16 \mathrm{c}\mathrm{m}$

Therefore, the final image is at distance 16 cm from the mirror. But, this image will be real.

This is because ray of light is travelling from right to left.