Question on lenses (as level)

A converging lens of focal length 250 mm forms a sharp image of an illuminated object on a screen, so that the linear magnification is 50. Without moving the object, the positions of the lens and screen are then altered so that a sharp image is again formed on the screen, but this time with a linear magnification of 100.

Through what distance, and in what direction relative to the object, has the lens been moved?​