[tex]\large\boxed{\begin{array}{l}\underline{\rm Divis\tilde ao\,de\,frac_{\!\!,}\tilde oes}\\\sf repete\,a\,1^a~2~e~multiplica\,pelo\,inverso\,da\,2^a.\\\sf\bigg(-\dfrac{21}{4}\bigg)\div(+7)=\bigg(-\dfrac{\diagdown\!\!\!\!\!\!21^3}{4}\bigg)\cdot\bigg(\dfrac{1}{\backslash\!\!\!7}\bigg)\\\\\sf\bigg(-\dfrac{21}{4}\bigg)\div(+7)=-\dfrac{3}{4}\end{array}}[/tex]
