Problem 5.35

A thin converging lens with focal length \(f=25 \mathrm{~cm}\) projects the image of an object on a screen removed from the lens by a distance \(l=5.0 \mathrm{~m}\). Then the screen was drawn closer to the lens by a distance \(\Delta l=18 \mathrm{~cm} .\) By what distance should the object be shifted for its image to become sharp again?