7.11.3 Can you answer these questions?

7.11.3.1 Little complicated representation of fraction with ProfCollege

https://tex.stackexchange.com/landing/r/digest?cta=question&id=582472

Is it possible to produce representation of this fraction with ProfCollegepackage ? 
My MWE : 
\documentclass[12pt]{article} 
\usepackage{mathtools} 
\usepackage{ProfCollege} 
\usepackage{tikz} 
\begin{... 
[teaching]
 

asked by Aviroum https://tex.stackexchange.com/landing/r/digest?cta=user&id=35785 1 vote

7.11.3.2 Two labels in the same matrix node

https://tex.stackexchange.com/landing/r/digest?cta=question&id=582063

I'd like to label two objects (two characters) in the same matrix node, in such a way to draw an arrow from the node above to each of the objects in the lower node. More precisely, I would like to ... 
[tikz-matrix]
 

asked by Edoardo Cavirani https://tex.stackexchange.com/landing/r/digest?cta=user&id=234582 1 vote

answered by Zarko https://tex.stackexchange.com/landing/r/digest?cta=user&id=18189 0 votes

7.11.3.3 How to learn LaTeX internals?

https://tex.stackexchange.com/landing/r/digest?cta=question&id=582371

I've read the LaTeX Companion and the TeXbook, but I am still struggling to understand how LaTeX works. 
How \DeclareOption works? 
Why should I end some lines with %? 
How penalty works? 
Where \if@... 
[packages] [tex-core] [learning]
 

asked by nowox https://tex.stackexchange.com/landing/r/digest?cta=user&id=85416 1 vote