After reviewing the material in the link, I can't help but think that it is irrelevant whether it is ≤ or as long as there is only one ≤ or ≥ sign in each number less than x less than number i.e.
-3≤x<4
OR
-3<x≤4
Is that correct?
-3≤x<4
OR
-3<x≤4
Is that correct?