As per <= sign the line should be solid
Next
Let's isolate x and y
[tex]\\ \sf\longmapsto y\leqslant 12x+4[/tex]
[tex]\\ \sf\longmapsto 12x-y\geqslant 4[/tex]
[tex]\\ \sf\longmapsto 0-0\geqslant 4[/tex]
Shading should go below the line towards origin