Which of the following expressions represents the phrase “19 less than a number” ?

n - 19

Step-by-step explanation:

This expression shows 19 less than a number because you dont know what the number is, you just know that the answer needs to be 19 less than it. So what do you do when you need the answer to be less than a number? You subtract! So using a variable for the unknown number and putting "-19" on it signifies an expression that represents "19 less than a number".

Hope this helped ^-^