Hi there!
If I'm correct your questions asks z less than or equal to 4.
Now, the signs that are being used here are ≤ and ≥
The line under those signs is meant to be -Equal to-
Now, we need to sign to be less than as well.
In your case z will be the smaller number or letter, so we will use this sign ≤
Your answer would look like z ≤ 4
I hope this helped! :D