Anna found the difference between thirteen and the product of four and a number. which expression represents this phrase, and what is its value if n = 3?

The first thing we must do for this case is to define a variable.
 We have then:
 n: unknown number.
 We write the algebraic expression:
 13 - 4n
 For n = 3 we have:
 13 - 4 (3) = 13 - 12 = 1
 
 An expression that represents this phrase is:
 13 - 4n
 its value if n = 3 is:
 1

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