Respuesta :
[tex]\underset{\leftarrow \qquad 19\qquad \to }{\stackrel{\blacktriangleright 7 \blacktriangleleft}{J\rule[0.35em]{5em}{0.25pt}K}\stackrel{12}{\rule[0.35em]{18em}{0.25pt}L}}[/tex]

[tex]\underset{\leftarrow \qquad 19\qquad \to }{\stackrel{\blacktriangleright 7 \blacktriangleleft}{J\rule[0.35em]{5em}{0.25pt}K}\stackrel{12}{\rule[0.35em]{18em}{0.25pt}L}}[/tex]