Why is it important to describe the variable in an expression?

Answer: They show numerical value. You have to make them clear.

you define it, and it lets you know how to properly write the equation ... If you want to solve for the unknowns using mathematical equations it is necessary to define the unknown variables i. e. what they represent in the real world so that the known relationships can be expressed in equation form

Step-by-step explanation:

its basically a value that can hold and amount depending on the value you give it