EBook and copyrights violations

There are books published by a local publisher which has all previous semester exam questions with their answers. This is specifically for Engineering. I would like to create an eBook similar to that and release it for free with ads for revenue generation. I have some details to present before asking questions. I would like to use mathematical equations as images & theoretical concepts as text data. 1. These books have both mathematical and theoretical content. 2. We have various app which can be used to create images of mathematical equations. 3. Previously I thought the theoretical content was directly copied from other publisher's books, but I was wrong. 4. The publisher modified the theoretical content to simplify it for students. 5. The circuit diagrams and other diagrams used in theoretical concepts may have been customized as well for simplicity. Questions: 1. If a mathematical question has an answer, can anyone claim copyright on the answer? For example, a mathematical questions like "Find whether the following system of equations are consistent. If so, solve them: 2x - y + z = 5; 3x + y - 2z = -1; x - 3y - z = 2". 2. I cannot imagine this question being answered any differently than what is stated in the syllabus. Sure the explanation of the answer may be slightly different like instead of writing "Adding equation (1), (2) & (3)", I may write "Adding equation (A), (B) & (C)". But is this even necessary? 3. Since we have a software which can generate images of mathematical equations, can I simply scan the mathematical equation and use it? Can I say that I got the image created instead of saying I copied it directly? 4. If I can use the scanned image of the equations from the book, what modifications are required from me to be able to use the scanned images? 5. Theoretical content is simply scientific concepts. For example, "Describe Laue's method for the determination of crystal structure." or "What are Brillouin zones? Explain using E-K diagrams". The concept is the same in almost any engineering book you choose, but can I use same exact content from this book in my ebook as well? 6. Since the theoretical concepts have diagrams as well, can I use the same diagrams? 7. Do I need the permission of the publisher for this? Can I do this without their permission since it is not their original content and they must have referenced other engineering books to draft this content? 8. If I need to modify the content to be able to use it, what should be the scale of modification? 60%, 70%, 90%? If i cannot get answers in a response to this question, can I have a call to get my doubts clarified?