Here is the problem: A converging lens with a focal length of 12.0 cm forms a virtual image 8.00 mm tall, 17.0 cm to the right of the lens. I am supposed to find the position of the object. I tried using the lens eq. 1/s + 1/s' = 1/f where s is the distance of the object from the lens, s' is the dist of the image from the lens, and f is the focal point. I got s to be 40.82 cm but I'm being told it's wrong. Is there something im missing here? Any tips and points would be great. Thanks!!