The expression is:
[tex] 4\ subtracted\ from\ a\ number [/tex]
A number that is unknown is called a variable. Variables can be any number. In this, make the variable n.
4 subtracted from a number is the same as 4 less than a number. 4 less than a number ⇒ - 4
Add the variable and your answer is:
[tex] n - 4 [/tex]
