# How do you define a variable and write an algebraic expression for the phrase: 12 less than a number?

Oct 14, 2015

The expression is $x - 12$.

#### Explanation:

$12$ less than a number means to subtract $12$ from that number.

So, $12$ less than $20$ is $8$, because is $20 - 12$, $12$ less than $12$ is $0$, because it's $12 - 12$, and so on.

But since you don't know which number you need to subtract from, it's a variable, and you can call it as you like, usually $x$.

So, using the variable we can write an expression that holds for any number, and which always means "take $12$ away from my number". If your number is $x$, the expression would be $x - 12$