Those of you who enjoy physics... I need help with Thin Lenses!

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Please answer as soon as possible if you know how to solve any of these questions. I'm stuck! 1. If I send a light ray parallel to a convex lens' principle axis, what does the light ray do in theory? (I've read all about this and I'm so confused because the wording is so weird and too similar to that of the concave lenses). 2. I place an object 35cm from a convex lens of focal length 12cm, where will the image form? 3. I have a compound lens whose focal length is 30cm, one of my lenses has a focal length of 20cm. What is the focal length of my second lens and what type of lens is it? Thanks in advance for any help!