Respuesta :

[tex]3|m+7|+9\ \textless \ 30\quad|-9\\\\3|m+7|\ \textless \ 21\quad|:3\\\\|m+7|\ \textless \ 7\\\\\\-7\ \textless \ m+7\ \textless \ 7\quad|-7\\\\-14\ \textless \ m\ \textless \ 0\\\\\\\boxed{m\in\big(-14,0\big)}[/tex]