Graphing on a number line Question

Hello;

I'm sorry Im trying to learn to use Latex while simultaneously mastering precalc so far it's not working.

I'm currently going over, graphing numbers on a number line and my book is doing only a fair job in explaining specific rules.

I understand that; [1<4] but why do I have to write the answer as; 1< or equal to x < or equal to 4

$\displaystyle 1\1eqx\1eq4$ if I can understand this reasoning, it would make the rest of my homework easier.

Thank You

Carolyn