The inequality "3 is equal to or greater than $x$" can be written as:

$x \leq 3$

In interval notation, this inequality is represented as:

$(-\infty, 3]$

This notation indicates that $x$ can take any value less than or equal to 3.

Would you like more details or have any other questions?

Here are 5 related questions:

1. How would you represent the inequality $x > 2$ in interval notation?
2. What is the interval notation for $1 \leq x \leq 5$?
3. How do you express the inequality $x \geq -4$ in interval notation?
4. Can you convert the inequality $x < -1$ into interval notation?
5. What is the interval notation for the inequality $x > 7$?

Tip: Remember, the square bracket $[$] in interval notation indicates that the endpoint is included, while the parenthesis $( )$ means the endpoint is not included.