Question

How do variables help you model real-world situations?

Answer 1

Variables help you model real-world situations by allowing you to assign certain symbols to a variable or factor. You can easily identify what are the dependent variables and independent variables. Also, you can easily know what to vary to know how much will change to an independent variable. You can predict what most likely happen in the real world.

Answer 2

A relationship between two quantities is often expressed as an equation  in two variables. For instance, the equation:

$y=3-4x$

is an equation in two variables x and y. Each order pair (a, b) will be a solution of this equation if and only if makes the equation to be true. That is, the ordered pair (1, -1) is a solution because:

$-1=3-4(1) \ is \ true$

In this way, the graph of an equation can  help you see relationships between real-life quantities. So, a real-world situation could be the life expectancy of a child, at birth, in the United States for selected years. So, if you are a researcher of a Research Institute you need to establish a relationship between the variable year and the variable life expectancy to know the life expectancy in each year.