Convert the interval notation \(( -\infty, 3 ]\) to inequality notation.

Step 1 ：The interval \(( -\infty, 3 ]\) means that the solution set includes all numbers less than or equal to 3, but does not include numbers less than negative infinity (since there are no numbers less than negative infinity).

Step 2 ：In inequality notation, we write this as \(x \leq 3\).