I hate to ask newbie questions in here, but can someone please
explain to me what is the difference betwenn a literal constant
and a variable??

Here's what my book says

Constants

Like a variable, a constant is a data storage location used by your program. Unlike a variable, the value stored in a constant can't be changed during program execution. C has two types of constants, each with its own specific uses.

Literal Constants

A literal constant is a value that is typed directly into the source code wherever it is needed. Here are two examples:

Int count = 20;
float tax_rate = 0.28;
I see no difference between this and a variable...