For a 35 mm camera, the equation + represents the focal length (A) of the lens that is needed to produce a clear photograph. The distance from the lens to the film, d, must be adjusted according to the distance from the lens to the object, do. If d; = x- + 2x - 3 x' - 9 2x-+ 10 and = x' + x- 2 ; what is 7 ? Explain how you found your answer. Paragr... V BIU A/ + . . . I