In photography, the distance `d` of an object from a lens, the distance `D` of the image from the lens and the focal length of the lens `f` are related through the following formula: `1/d+1/D=1/f` .

For each lens, `f` is a constant whereas `d` and `D` are variables, in a particular instant, a racing car is moving away from the lens at a rate of `250 km h^(-1)` , in which direction and how fast, in `km h^(-1)` , will the image be moving?