The inequality y <= (-1/3)x + 3 will be the shaded region composed of regions C and D. These regions are below the line with negative slope.
The inequality y >= 3x+2 is the shaded region composed of regions A and D which are above the positive sloped line.
The overlapping region is region D. This region is found in BOTH shaded solution sets of the two inequalities.
This is why region D is the final answer.