Ok so I have this problem where I have a system of two lenses. All I know is that the distance between the object and the first lens is 30cm, the distance between the object and the final image is 70cm, the focal distance of the first lens is 20 and the total magnification is -0.666. I need to find the focal distance of the second lens and the distance between lenses 1 and 2.
Now I've tried calculating the parameters of the first lens' image (it should be 60cm past the first lens and the magnification should be -2). My problem is that if I now use this image as an object for the second lens and solve the equations, I obtain absurd results (values should put the lens between the first lens and the final image but they don't).
How should I go about solving such a problem?