Problem 5.31

A point source is located at a distance of \(20 \mathrm{~cm}\) from the front surface of a symmetrical glass biconvex lens. The lens is \(5.0 \mathrm{~cm}\) thick and the curvature radius of its surfaces is \(5.0 \mathrm{~cm} .\) How far beyond the rear surface of this lens is the image of the source formed?