We are given an expression "4n"
The question says to evaluate this expression when n = 5
Here, evaluation simply means, finding the value of "4n" when n = 5. This is a simple problem of substitution. By substitution I mean replacing every occurence of n in the given expression by 5. This would be done as follows:
Given expression = 4n
Note that here 4 is being multiplied to n.
Replacing n by 5, we get the result as:
From here, we can conclude that the value of expression "4n" for n = 5 will be 20.