#### Answer

$(-\infty, 3]$
Refer to the image below for the graph.

#### Work Step by Step

The solution set of the given inequality includes all the numbers that are less than or equal to $3$.
The set includes all the numbers to the left of $3$ so $-\infty$ will be used on the left side of the interval notation.
The highest number is $3$ so a bracket will be used on the right side of the interval.
Thus, the interval notation equivalent of the given inequality is: $(-\infty, 3]$
To graph the solution set on a number line, plot a solid dot at $x=3$ then shade the region to its left.
(refer to the attached image in the answer part above)