Answer:
[tex]\boxed {\tt 21n}[/tex]
Step-by-step explanation:
We want to write the product of a number and 21 as an algebraic expression. Let's define "a number" as the variable n.
We know that "product" means multiplication. The product of a number, n, and 21 is equal to multiplying n and 21.
[tex]n*21[/tex]
21 and n can be flipped due to the commutative property of multiplication.
[tex]21*n[/tex]
[tex]21n[/tex]
The product of a number and 21 is 21n.
