Source
Complète
\par\vspace{3mm}\par
\Eqalign{ \frac{\rnode{A}{21}}{\rnode{B}{12}}\quad&= \quad\frac{\ldots\times\ldots}{\ldots\times\ldots}\quad= \quad\frac{\rnode{C}{\strut\ldots}}{\rnode{D}{4}}\kern1cm &\frac{\rnode{E}{8}}{\rnode{F}{20}}\quad&= \quad\frac{\ldots\times\ldots}{\ldots\times\ldots}\quad= \quad\frac{\rnode{G}{\strut\ldots}}{\rnode{H}{5}}\kern1cm& \frac{\rnode{I}{24}}{\rnode{J}{\strut\ldots}}\quad& =\quad\frac{\ldots\times\ldots}{\ldots\times\ldots}\quad= \quad\frac{\rnode{K}{2}}{\rnode{L}{3}}\cr \cr \cr \frac{21}{35}\quad&=\quad\frac{\ldots\times\ldots}{\ldots\times\ldots}\quad= \quad\frac{3}{\ldots}&\frac{\ldots}{24}\quad&\quad \frac{\ldots\times\ldots}{\ldots\times\ldots}\quad= \quad\frac23&\frac{48}{42}&=\quad \frac{\ldots\times\ldots}{\ldots\times\ldots}\quad= \quad\frac{\ldots}{7}\cr }
\ncarc[arcangle=60,nodesep=1mm]{->}{A}{C}
\ncput*{\small$\div\ldots$}
\ncarc[arcangle=-60,nodesep=1mm]{->}{B}{D}
\ncput*{\small$\div\ldots$}
\ncarc[arcangle=60,nodesep=1mm]{->}{E}{G}
\ncput*{\small$\div\ldots$}
\ncarc[arcangle=-60,nodesep=1mm]{->}{F}{H}
\ncput*{\small$\div\ldots$}
\ncarc[arcangle=60,nodesep=1mm]{->}{I}{K}
\ncput*{\small$\div\ldots$}
\ncarc[arcangle=-60,nodesep=1mm]{->}{J}{L}
\ncput*{\small$\div\ldots$}