Two lenses are placed along the x axis, with a diverging lens of focal length −7.10 cm on the left and a converging lens of focal length 17.0 cm on the right. When an object is placed 12.0 cm to the left of the diverging lens, what should the separation s of the two lenses be if the final image is to be focused at x = ∞?

Two lenses are placed along the x axis, with a diverging lens of focal length −7.10 cm on the left and a converging lens of focal length 17.0 cm on the right. When an object is placed 12.0 cm to the left of the diverging lens, what should the separation s of the two lenses be if the final image is to be focused at x = ∞?