\(\frac{1}{f}=\frac{1}{v_{1}}+\frac{1}{u_{1}} ;-\frac{1}{15}=\frac{1}{v_{1}}-\frac{1}{40} \Rightarrow \frac{1}{v_{1}}=\frac{1}{-15}+\frac{1}{40}\)

\(v_{1}=-24 \,\mathrm{cm}\)

When object is displaced by \(20 \,\mathrm{cm}\) towards mirror Now, \(u_{2}=-20\, \mathrm{cm}\)

\(\frac{1}{f}=\frac{1}{v_{2}}+\frac{1}{u_{2}} ; \frac{1}{-15}=\frac{1}{v_{2}}-\frac{1}{20} \Rightarrow \frac{1}{v_{2}}=\frac{1}{20}-\frac{1}{15}\)

\(v_{2}=-60\, \mathrm{cm}\)

So, the image will be shift away from mirror by \((60-24) \mathrm{cm}=36 \,\mathrm{cm}\)