$(-\infty, 1]$ Refer to the image below for the graph.
Work Step by Step
The inequality is "x is less than or equal to 1." This inequality includes all numbers from 1 to its left. This means that the equivalent interval notation of this inequality will have: (i) negative infinity and parenthesis on the left; and (ii) 1 and bracket on the right Thus, the interval notation is: $(-\infty, 1]$ To graph this interval, plot a hole (or hollow dot) at $1$, then shade the region to its left. (refer to the attached image in the answer part above)