Is applying a formula a kind of reasoning?

Question

Supposed I have a set of simple rules, e.g.

if A is between 10 and 20 and B is between 3 and 5, then use 3

and this rules are used in some kind of (more or less) mathematical formula (for example, A + B = C), would you count this as a form of reasoning or inference of a knowledge based system?

You have a knowledge base (the rules) and you get a result (a decision) by applying this rules in a specific way.

I'm curious about your opinions. Thanks!