I am looking for an easy answer of how to fill an area defined by an inequality like for example y >= 4 - x in latex.
I would also appreciate if you could tell where the options go as well, for example I might be intereseted in replacing the line by a dashed line or I might be interested that the area has transparency in case it croses with other areas.
As guidance, I would like to fill the area under the two straight lines of this picture:
KR

fillbetweenlibrary that comes withpgfplots. – Sep 01 '19 at 14:11