Before one can know how the graph looks like, one needs to evaluate the inequality first.
The inequality 4 < n +6 < 9 can be simplified by subtracting each the right hand, the left hand and the center by 6.
4-6 < n +6 -6 < 9- 6
-2 < n < 3
Therefore the line graph looks has open circles on -2 and 3 and a shaded line between them.