This question should be pretty easy. I’m just not sure how to put it in an expression.

Answer:
The correct answer is 5n
Step-by-step explanation:
If you plug the input into each equation and it doesn't give you the output then the equation is incorrect. If you plug it into an equation and it gives you the output then that equation is correct.
Ex. 5n or 5(2) = 10
5(4) = 20
5(6) = 30
5(8) = 40
5(10) = 50