Hi, my LaTeX friend 1. Yes, the target you showed can be achieved by the method provided yesterday. 2. This is the simplest way to get your goal since you required LaTeX and that is THE LaTeX basis definitely. 3. The code provided certainly won't work. I AM expecting you to find the solution by yourself. That is the fun part. That is how to learn LaTeX IMHO. Consider a unit square where x, a, x, b are located at the 4 corners, and use the coordinates to put and plot. 4. Using Google search with key words like "picture", "latex", "put", or "line" will give sufficient info for you to pick up what you need. 5. My apology that a full solution is not due at this point. Sorry. Sincerely yours